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A Review on Graphene Oxide Two-dimensional Macromolecules: from Single Molecules to Macro-assembly
Wen-Zhang Fang, Li Peng, Ying-Jun Liu, Fang Wang, Zhen Xu, Chao Gao
Corrected proof , doi: 10.1007/s10118-021-2515-1
[Abstract](126) [FullText HTML](10) [PDF 141494KB](0)
Graphene oxide (GO), which consists of two-dimensional (2D) sp2 carbon hexagonal networks and oxygen-contained functional groups, has laid the foundation of mass production and applications of graphene materials. Made by chemical oxidation of graphite, GO is highly dispersible or even solubilized in water and polar organic solvents, which resolves the hard problem of graphene processing and opens a door to wet-processing of graphene. Despite its defects, GO is easy to functionalize, dope, punch holes, cut into pieces, conduct chemical reduction, form lyotropic liquid crystal, and assemble into macroscopic materials with tunable structures and properties as a living building block. GO sheet has been viewed as a single molecule, a particle, as well as a soft polymer material. An overview on GO as a 2D macromolecule is essential for studying its intrinsic properties and guiding the development of relevant subjects. This review mainly focuses on recent advances of GO sheets, from single macromolecular behavior to macro-assembled graphene material properties. The first part of this review offers a brief introduction to the synthesis of GO molecules. Then the chemical structure and physical properties of GO are presented, as well as its polarity in solvent and rheology behavior. Several key parameters governing the ultimate stability of GO colloidal behavior, including size, pH and the presence of cation in aqueous dispersions, are highlighted. Furthermore, the discovery of GO liquid crystal and functionalization of GO molecules have built solid new foundations of preparing highly ordered, architecture-tunable, macro-assembled graphene materials, including 1D graphene fibers, 2D graphene films, and 3D graphene architectures. The GO-based composites are also viewed and the interactions between these target materials and GO are carefully discussed. Finally, an outlook is provided in this field, where GO is regarded as macromolecules, pointing out the challenges and opportunities that exist in the field. We hope that this review will be beneficial to the understanding of GO in terms of chemical structure, molecular properties, macro-assembly and potential applications, and encourage further development to extend its investigations from basic research to practical applications.
Tunable Lower Critical Solution Temperature of Poly(butyl acrylate) in Ionic Liquid Blends
Lie Chen, Jin Huang, Cong Zhao, Jia-Jia Zhou, Ming-Jie Liu
Corrected proof , doi: 10.1007/s10118-021-2522-2
[Abstract](115) [FullText HTML](9) [PDF 337KB](0)
We describe the lower critical solution temperature (LCST)-type phase behavior of poly(butyl acrylate) (PBA) dissolved in hydrophobic 1-alkyl-3-methylimidazolium bis{(trifluoromethyl) sulfonyl}amide ionic liquids (ILs). The temperature-composition phase diagrams of these PBA/ILs systems are strongly asymmetric with the critical composition shifted to low concentrations of PBA. As the molecular weight increases from 5.0×103 to 2.0×104, the critical temperature decreases by about 67 °C, and the critical composition shifts to a lower concentration. Furthermore, the LCST of PBA/ILs system increases as increasing the alkyl side chain length in the imidazolium cation. Using IL blends as solvents, the LCST of PBA can be tuned almost linearly over a wide range by varying the mixing ratio of two ionic liquids without modifying the chemical structure of the polymers.
A Conjugated Copolymer Bearing Imidazolium-based Ionic Liquid: Electrochemical Synthesis and Electrochromic Properties
Xiao-Jing Lv, Li-Bin Xu, Liang Qian, Yuan-Yuan Yang, Zhi-Yi Xu, Jin Li, Cheng Zhang
Corrected proof , doi: 10.1007/s10118-021-2525-z
[Abstract](68) [FullText HTML](9) [PDF 1074KB](0)
An imidazolium-based ionic liquid (IL) modified triphenylamine derivative, namely 1-(4-((4-(diphenylamino)benzoyl) oxy)butyl)-3-methyl imidazole tetrafluoroborate (TPAC6IL-BF4), was designed and synthesized, and further applied with 3,4-ethylene dioxythiophene (EDOT) to prepare conjugated copolymer P(EDOT:TPAC6IL-BF4) via electrochemical polymerization. The cyclic voltammetry curves show that the copolymer P(EDOT:TPAC6IL-BF4) possesses two pairs of redox peaks, which should be ascribed to the redox behaviors of EDOT and triphenylamine. The ultraviolet-visible (UV-Vis) absorption spectrum of P(EDOT:TPAC6IL-BF4) exhibits one maximum absorption peak at 580 nm and a small shoulder characteristic peak at 385 nm under neutral state which are assigned to π-π* conjugated structure of EDOT and triphenylamine. After being applied at the positive voltage, the copolymer color changes from dark blue to light blue, which is close to the color of poly(3,4-ethylenedioxythiophene) (PEDOT). Surprisingly, the copolymer P(EDOT:TPAC6IL-BF4) shows shorter switching time of 0.37 s, 0.30 s at 580 nm and 0.38 s, 0.45 s at 1100 nm compared with PEDOT. It is more intriguing that the copolymer P(EDOT:TPAC6IL-BF4) exhibits electrochromism even in free supporting electrolyte. The results confirm that the existence of imidazolium-based ionic liquid has an improvement on the ion diffusion properties and the switching time of conjugated polymer, which may provide a potential direction for the preparation of high-performance electrochromic materials.
Tailoring Morphology of PVDF-HFP Membrane via One-step Reactive Vapor Induced Phase Separation for Efficient Oil-Water Separation
Peng Huo, Cheng-Tang Zhong, Xiao-Peng Xiong
Corrected proof , doi: 10.1007/s10118-021-2527-x
[Abstract](51) [FullText HTML](10) [PDF 1105KB](0)
Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) receives increasing attention in membrane separation field based on its advantages such as high mechanical strength, thermal and chemical stability. However, controlling the microporous structure is still challenging. In this work, we attempted to tailor the morphology of PVDF-HFP membrane via a one-step reactive vapor induced phase separation method. Namely, PVDF-HFP was dissolved in a volatile solvent and then was cast in an ammonia water vapor atmosphere. After complete evaporation of solvent, membranes with adjustable porous structure were prepared, and the microstructures of the membranes were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction characterizations. Based on the results, a mechanism of dehydrofluorination induced cross-linking of PVDF-HFP has been suggested to understand the morphology tailoring. To our knowledge, this is the first report of one-step reactive vapor induced phase separation strategy to tailor morphology of PVDF-HFP membrane. In addition, the membranes prepared in the ammonia water vapor exhibited enhanced mechanical strength and achieved satisfactory separation efficiency for water-in-oil emulsions, suggesting promising potential.
Conformational and Dynamical Evolution of Block Copolymers in Shear Flow
Xiang-Xin Kong, Wen-Duo Chen, Feng-Chao Cui, Yun-Qi Li
Corrected proof , doi: 10.1007/s10118-021-2523-1
[Abstract](89) [FullText HTML](23) [PDF 2810KB](0)
Conformation and dynamical evolution of block copolymers in shear flow is an important topic in polymer physics that underscores the forming process of various materials. We explored deformation and dynamics of copolymers composed of rigid or flexible blocks in simple shear flow by employing multiparticle collision dynamics integrated with molecular dynamics simulations. We found that compared with the proportion between rigid and flexible blocks, the type of the central blocks plays more important role in the conformational and dynamical evolution of copolymers. That is, if the central block is a coil, the copolymer chain takes end-over-end tumbling motion, while if the central block is a rod, the copolymer chain undergoes U-shape or S-shape deformation at mid shear rate. As the shear strength increases, all copolymers behave similar to flexible polymers at high shear rate. This can be attributed to the fact that shear flow is strong enough to overcome the buckling force of the rigid blocks. These results provide a deeper understanding of the roles played by rod and coil blocks in copolymers for phase interface during forming processing.
Coalescence Suppression in Flowing Polymer Blends Using Silica Rods with Different Surface Chemistries
Si-Ying Xiang, Li-Sa-Ya Ye, Ya-Jiang Huang, Ya-Dong Lv, Mi-Qiu Kong, Guang-Xian Li
Corrected proof , doi: 10.1007/s10118-021-2526-y
[Abstract](89) [FullText HTML](38) [PDF 796KB](0)
Silica rods with homogeneous (hydrophilic or hydrophobic) and amphiphilic surface properties were synthesized and their efficiencies in suppressing the flow-induced droplet coalescence of immiscible polyisobutylene (PIB)/polydimethylsiloxane (PDMS) blends were evaluated via in situ visualization technique. The flow-induced coalescence behavior of blends was found to strongly depend on the surface nature and concentration of silica rods added as well as the blend ratio. While a trace amount of rods promoted coalescence, all kinds of rods demonstrated a morphology refinement effect at high rod concentrations. Good compatibilization effects were obtained at high rod concentrations, especially for hydrophilic and amphiphilic rods. Based on confocal laser scanning microscopy results, these phenomena observed were interpreted reasonably in terms of the selective distribution and aggregation of silica rods, which were suggested to be decisive for the stabilization mechanism and efficiency of these rods.
High Strength Electrospun Single Copolyacrylonitrile (coPAN) Nanofibers with Improved Molecular Orientation by Drawing
Tang-Cheng Xu, Dong-Hua Han, Yong-Mei Zhu, Gai-Gai Duan, Kun-Ming Liu, Hao-Qing Hou
Corrected proof , doi: 10.1007/s10118-021-2516-0
[Abstract](74) [FullText HTML](30) [PDF 2243KB](1)
High-performance carbon nanofibers are highly dependent on the performance of their precursors, especially polyacrylonitrile (PAN). In this work, the copolymer of PAN (coPAN) was synthesized for electrospinning. A self-assembling set-up was used for the stretching of single coPAN nanofibers. FTIR and Raman spectroscopies were used to characterize the chemical structure of coPAN nanofibers. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to monitor the morphology of single coPAN nanofibers under different drawing times. Micro-tensile test was used to determine the mechanical properties of single coPAN nanofibers. The results indicated that the drawing led to an increase in degree of molecular orientation along the fiber axis from 0.656 to 0.808, tensile strength from 304 MPa to 595 MPa, and modulus from 3.1 GPa to 12.4 GPa. This research would provide fundamental information of high-performance electrospun coPAN nanofibers and offer opportunities for the preparation of high-performance carbon nanofibers.
Visualization of Two-dimensional Single Chains of Hybrid Polyelectrolytes on Solid Surface
Lan-Lan Zhang, Wen-Ke Miao, Li-Jun Ren, Yu-Kun Yan, Wei Wang
Corrected proof , doi: 10.1007/s10118-021-2520-4
[Abstract](108) [FullText HTML](38) [PDF 1005KB](0)
The polyacidic character of polyoxometalate (POM) clusters endows high ionic conductivity, making these clusters good candidates for solar and fuel cells. Covalent bonding of clusters to polymer chains creates poly(POM)s that are polyelectrolytes with both cluster functions and polymer performance. Thus, solution-processable poly(POM)s are expected to be used as key materials in advanced devices. Further understanding of poly(POM)s will optimize the preparation process and improve device performance. Herein, we report a study of the first linear poly(POM)s by directly visualizing the chains using scanning transmission electron microscopy. Compared with traditional polymers, individual clusters of poly(POM)s can be directly visualized because of the resistance to electron-beam damage and the high contrast of the tungsten POM pendants. Thus, cluster aggregates with diverse shapes were observed. Counting the number of clusters in the aggregates allowed the degree of polymerization and molecular weight distribution to be determined, and studying the aggregate shapes revealed the presence of a curved semi-rigid chain in solution. Further study of shape diversity revealed that strong interactions between clusters determine the diverse chain shapes formed during solution processing. Fundamental insight is critical to understanding the formation of poly(POM) films from solutions as key functional materials, especially for fuel and solar cells.
Highly Transparent and Colorless Polyimide Film with Low Dielectric Constant by Introducing Meta-substituted Structure and Trifluoromethyl Groups
Hong-Tao Zuo, Feng Gan, Jie Dong, Peng Zhang, Xin Zhao, Qing-Hua Zhang
Corrected proof , doi: 10.1007/s10118-021-2514-2
[Abstract](51) [FullText HTML](30) [PDF 725KB](0)
An effective design strategy for preparing highly transparent polyimide film with low dielectric constant is presented. The key to the strategy is to simultaneously introduce meta-substituted structure and trifluoromethyl in polymer chains. By using this design strategy, a highly transparent polyimide film with low-k was synthesized from 3,5-diaminobenzotrifluoride (m-TFPDA) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) through a two-step method. The obtained m-TFPDA/6FDA (CPI) film (~30 μm) possesses high optical transparency (λcutoff=334 nm, T450nm=85.26%, Haze=0.31) and is close to colorless (L*=96.03, a*=−0.34, b*=2.12, yellow index=3.96). The intrinsic k and dielectric loss value of the film are 2.27 and 0.0013 at 10 kHz, respectively. More importantly, such low dielectric performance could remain stable up to 280 °C, and the film shows a low moisture rate (~0.51%), which helps to maintain the low-k property stability in different humid environments. Meanwhile, the film also shows good thermal stability and mechanical properties, with a glass transition temperature (Tg) of 296 °C and the 5 wt% decomposition temperature (Td,5%) of 522 °C under N2. The tensile strength and tensile modulus of the film are 85.1 MPa and 1.96 GPa, respectively. In addition, the film is soluble in common solvents, which allows simple solution processing and low-cost, continuous roll-to-roll processes. This design strategy is beneficial to improving the transparency, lightening yellow color, lowering the dielectric constant and meanwhile maintaining the comprehensive properties of polyimide films, which is mainly due to the introduced meta-substituted and trifluoromethyl structures effectively inhibiting the transfer of charge transfer complex (CTC) effects and increasing the free volume of film. This design strategy could also be extended to other high-performance polymer systems.
Enhanced Gas Separation Performance by Embedding Submicron Poly(ethylene glycol) Capsules into Polyetherimide Membrane
Ying-Ying Ma, Min Liu, Jing-Tao Wang, Bin Zhu, Yi-Fan Li
Corrected proof , doi: 10.1007/s10118-021-2521-3
[Abstract](85) [FullText HTML](46) [PDF 1987KB](3)
Recently, hollow filler as an emerging concept is attracting more attention in preparation of mixed matrix membranes (MMMs). Herein, poly(ethylene glycol) microcapsules (PMC) are synthesized via distillation precipitation polymerization and embedded into the polyetherimide (Ultem®1000) matrix to fabricate MMMs for CO2 capture. The PMC exhibits a preferential hollow structure within the Ultem matrix to furnish highways within membrane, and thus achieve high gas permeability. Meanwhile, the favorable affinity of poly(ethylene glycol) (PEG) microcapsule with ether oxygen group (EO) towards CO2 enhances the CO2 solubility selectivity. Such integration of physical and chemical microenvironments in the as-designed PEG microcapsule affords highly enhanced CO2 separation performance. Compared to pristine Ultem®1000, the membrane with 2.5 wt% PMC loading exhibits 310% increment in CO2 permeability and 22% increment in CO2/N2 selectivity, which shows the promising prospects of designing PEG-containing microcapsules as the filler of MMMs for CO2 capture.
Tough Double Metal-ion Cross-linked Elastomers with Temperature-adaptable Self-healing and Luminescence Properties
Qi-Yan Yin, Cheng-Hao Dai, Huan Chen, Kai Gou, Hong-Zhou Guan, Peng-Han Wang, Jing-Tao Jiang, Geng-Sheng Weng
Corrected proof , doi: 10.1007/s10118-021-2517-z
[Abstract](195) [FullText HTML](57) [PDF 820KB](0)
Smart materials with a combination of tough solid-like properties, fast self-healing and optical responsiveness are of interests for the development of new soft machines and wearable electronics. In this work, tough physically cross-linked elastomers that show high mechanical strength, intriguing temperature-adaptable self-healing and fluorochromic response properties are designed using aluminum (Al) and fluorescent europium (Eu) ions as cross-linkers. The ionic Al-COOH binding is incorporated to construct the strong polymer network which mainly contributes to the mechanical robustness of the elastomer consisting of two interpenetrated networks. The Eu-iminodiacetate (IDA) coordination is mainly used to build the weaker but more dynamic network which dominate the elasticity, self-healing and luminescence of the elastomer. Moderate Eu3+ and Al3+ contents give these supramolecular elastomers high toughness. The temperature-sensitive Eu-IDA coordination enables tunable self-healing rate and efficiency along with fast Eu-centered “ON/OFF” switchable red emission. The mechanical, self-healing and luminescence properties of these elastomers can be adjusted by tuning the ratio of the two types of metal ions. This elastomer is potentially applicable for biosensors, wearable optoelectronics and anticounterfeiting materials.
Photoinduced Reversible Solid-to-Liquid Transitions and Directional Photofluidization of Azobenzene-containing Polymers
Shuo-Feng Liang, Chen Nie, Jie Yan, Qi-Jin Zhang, Si Wu
Corrected proof , doi: 10.1007/s10118-021-2519-x
[Abstract](145) [FullText HTML](47) [PDF 798KB](0)
Photoinduced reversible liquefaction and solidification of polymers enable processing and healing of polymers with light. Some azobenzene-containing polymers (azopolymers) exhibit two types of photoinduced liquefaction properties: photoinduced reversible solid-to-liquid transition and directional photofluidization. For the first type, light switches the glass transition temperature (Tg) values of azopolymers and induces reversible solid-to-liquid transitions. For the second type, polarized light guides solid azopolymers to flow along the polarization direction. Here, we compare the two types of photoliquefaction and discuss their mechanisms. Recent progresses and applications based on photoliquefaction of azopolymers are also highlighted.
Unusual Spherulitic Morphology of Poly(propylene fumarate)
Xiao-Yu Meng, Yi Li, Shu-Fang Yao, Xue-Wei Wei, Hai-Mu Ye
Corrected proof , doi: 10.1007/s10118-021-2518-y
[Abstract](144) [FullText HTML](56) [PDF 817KB](3)
Spherulites are the most common crystalline morphology and thus the visual expression of crystal structures for polymers. The diversified patterns have provided intuitive morphology probes for various crystallization behaviors, while the correlations between them are still needed to be enriched. In this work, the complicated spherulitic morphology of poly(propylene fumarate) (PPF), which is sensitive to crystallization temperature, is investigated. PPF melt, respectively, crystallizes into rough spherulites, regularly banded spherulites, and spherulites containing both two kinds of morphology at low, high, and mediate temperatures. By systematically assaying, it is clear that the growth axis along the radial direction changes from a-axis to b-axis as the crystallization temperature increases, which leads to the formation of unique crystallization-temperature-dependent spherulites. Based on detailed characterization of Fourier transform infrared spectroscopy, the packing state of the specific hydrogen bonds of “C=C―H···O=C―C=C” in PPF crystal lattices is determined, and furthermore, the mechanism for temperature-dependent selection of growth axes for PPF spherulites in melt is reasonably speculated.
Robust and Self-healable Antibiofilm Multilayer Coatings
Chao Zhou, Jun-Tao Zhou, Cheng-Ju Sheng, Dicky Pranantyo, Yan Pan, Xiao-Jia Huang
Corrected proof , doi: 10.1007/s10118-021-2513-3
[Abstract](202) [FullText HTML](73) [PDF 11617KB](0)
The infection induced by implantation of biomedical materials may result from the biofilm formation after bacteria attachment. Hence, the antibiofilm surface coating represents a novel technique to improve the antibacterial activity of biomedical materials. The traditional antibiofilm surface coatings exhibited some disadvantages and provided a limited service life. In this work, we used polyethyleneimine grafted 3-maleimidopropionic acid (PEIM) and poly(acrylic acid) grafted 2-furfurylamine (PAAF) to achieve robust and self-healable crosslinked multilayer coatings, employing Layer-by-Layer (LbL) self-assembly technique and Diels-Alder reaction. Then, thiol-terminated poly((3-acrylamidopropyl) trimethylammonium chloride) (PAMPTMA-SH) was grafted onto the crosslinked multilayer coating by thiol-ene click reaction to form a novel multilayer coating (PEIM/PAAF)10-PAMPTMA. We found that this coating showed robust and self-healable activity, and significantly inhibited the bacterial growth and biofilm formation after infection with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by in vitro and in vivo assays for 120 h. In addition, the multilayer coating did not induce significant hemolysis or affect the cell viability of red blood cells. In vivo studies also showed that (PEIM/PAAF)10-PAMPTMA coating efficiently blocked the infiltration of inflammatory cells and gene expression in the mouse skin challenged with E. coli or S. aureus. Taken together, these results showed that the prepared multilayer coating exhibited strong antibiofilm activity and provided a new strategy for the application of highly efficient antibiofilm surface coating of biomedical materials.
Stereocomplex Crystallization in Asymmetric Diblock Copolymers Studied by Dynamic Monte Carlo Simulations
Ying Xu, Jun Yang, Zong-Fa Liu, Zhi-Ping Zhou, Zhao-Peng Liang, Tong-Fan Hao, Yi-Jing Nie
Corrected proof , doi: 10.1007/s10118-021-2512-4
[Abstract](184) [FullText HTML](68) [PDF 654KB](0)
Stereocomplex crystallization in asymmetric diblock copolymers was studied using dynamic Monte Carlo simulations, and the key factor dominating the formation of stereocomplex crystallites (SCs) was uncovered. The asymmetric diblock copolymers with higher degree of asymmetry exhibit larger difference between volume fractions of beads of different blocks, and local miscibility between different kinds of beads is lower, leading to lower SC content. To minimize the interference from volume fraction of beads, the SC formation in blends of asymmetric diblock copolymers was also studied. For the cases where the volume fractions of beads of different blocks are the same, similar local miscibility between beads of different blocks and similar SC content was observed. These findings indicate that the volume fraction of beads of different blocks is a key factor controlling the SC formation in the asymmetric diblock copolymers. The SC content can be regulated by adjusting the difference between the contents of beads of different blocks in asymmetric diblock copolymers.
Styrene-containing Phosphine-sulfonate Ligands for Nickel- and Palladium-catalyzed Ethylene Polymerization
Shabnam Behzadi, Chen Zou, Bang-Pei Yang, Chen Tan, Chang-Le Chen
Corrected proof , doi: 10.1007/s10118-021-2509-z
[Abstract](380) [FullText HTML](97) [PDF 402KB](1)
A series of phosphine-sulfonate ligands bearing 2-, 3- and 4-vinylphenyl on the phosphorus atom were designed, synthesized, characterized and investigated in Ni- and Pd-catalyzed ethylene polymerization. The structure of the phosphine-sulfonate Pd complex bearing 2-vinylphenyl on the phosphorus atom showed 2,1-insertion for the 2-vinyl group. The phosphine-sulfonate Ni complex bearing 2-vinylphenyl resulted in significantly increased thermal stability and polyethylene molecular weights (Mn = 3.69×104 g·mol−1 at 80 °C) versus the counterparts bearing 3-/4-vinyl groups as well as previously reported phosphine-sulfonate Ni complexes bearing bulky biaryl substituents.
Antimicrobial Properties and Application of Polysaccharides and Their Derivatives
Gui-Xue Xia, Yue-Ming Wu, Yu-Fang Bi, Kang Chen, Wei-Wei Zhang, Shi-Qi Liu, Wen-Jing Zhang, Run-Hui Liu
Corrected proof , doi: 10.1007/s10118-021-2506-2
[Abstract](307) [FullText HTML](118) [PDF 1774KB](1)
With the quick emergence of antibiotic resistance and multi-drug resistant microbes, more and more attention has been paid to the development of new antimicrobial agents that have potential to take the challenge. Polysaccharides, as one of the major classes of biopolymers, were explored for their antimicrobial properties and applications, owing to their easy accessibility, biocompatibility and easy modification. Polysaccharides and their derivatives have variable demonstrations and applications as antimicrobial agents and antimicrobial biomaterials. A variety of polysaccharides, such as chitosan, dextran, hyaluronic acid, cellulose, other plant/animal-derived polysaccharides and their derivatives have been explored for antimicrobial applications. We expect that this review can summarize the important progress of this field and inspire new concepts, which will contribute to the development of novel antimicrobial agents in combating antibiotic resistance and drug-resistant antimicrobial infections.
Yttrium-catalyzed cis-1,4-Selective Polymerization of 2-(4-Halophenyl)-1,3-Butadienes and Their Copolymerization with Isoprene
Jian-Ming Huang, Chang-Guang Yao, Shi-Hui Li, Dong-Mei Cui
Corrected proof , doi: 10.1007/s10118-021-2505-3
[Abstract](251) [FullText HTML](81) [PDF 493KB](2)
Polymerization of 2-(4-halophenyl)-1,3-butadiene (2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex ( 1 ) activated by [Ph3C][B(C6F5)4] and AliBu3 shows high cis-1,4-selectivity (>98%) for the polymerization of 2-XPB (2-XPB = 2-FPB, 2-ClPB and 2-BrPB) to afford halogenated plastic poly(dienes) with glass transition temperatures of 30–55 °C. Moreover, the copolymerization of 2-XPB with isoprene (IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%–100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation of cis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with nBuLi, CO2 and HCl.
Preparation of Hydrophilic UHMWPE Hollow Fiber Membranes by Chemically Bounding Silica Nanoparticles
Lian-Lian Fan, Jia-You Quan, Hao Zhang, Jun-Rong Yu, Zu-Ming Hu, Yan Wang
Corrected proof , doi: 10.1007/s10118-021-2507-1
[Abstract](331) [FullText HTML](76) [PDF 1896KB](0)
In this work, ultra-high molecular weight polyethylene (UHMWPE) microfiltration hollow fiber membranes prepared via the thermally induced phase separation (TIPS) method were modified by chemically bounding hydrophilic silica (SiO2) nanoparticles onto the surface to improve anti-fouling performance. A range of testing techniques including attenuated total reflection Flourier transformed infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), water contact angle, mechanical test, filtration and anti-fouling performance were carried out to discuss the influence of different modification conditions on the properties of the membranes. The prepared hollow fiber membranes display the significantly excellent performance when the vinyl trimethoxy silane (VTMS) concentration was 13%, the pH value of the hydrolyzate was 4 and the hydrolysis reaction time was 6 h. In particular, the hydrophilicity of modified membranes was improved effectively, resulting in the enhancement of membrane anti-fouling properties. The results of this work can be consulted for improving the anti-fouling performance of the UHMWPE microfiltration hollow fiber membrane applied in the field of water purification.
Benzotriazole Based 2D-conjugated Polymer Donors for High Performance Polymer Solar Cells
Zhi-Guo Zhang, Yang Bai, Yongfang Li
Corrected proof , doi: 10.1007/s10118-020-2496-5
[Abstract](311) [FullText HTML](78) [PDF 641KB](0)
To design high efficiency polymer solar cells (PSCs), it is of great importance to develop suitable polymer donors that work well with the low bandgap acceptors, providing complementary absorption, forming interpenetrating networks in the active layers and minimizing energy loss. Recently, we developed a series of two-dimension-conjugated polymers based on bithienylbenzodithiophene-alt-benzotriazole backbone bearing different conjugated side chains, generally called J-series polymers. They are medium energy bandgap (Eg) polymers (Eg of ca. 1.80 eV) with strong absorptions in the range of 400−650 nm, and exhibit ordered crystalline structures, high hole mobilities, and more interestingly, tunable energy levels depending on the structure variations. In this feature article, we highlight our recent efforts on the design and synthesis of those J-series polymer donors, including an introduction on the polymer design strategy and emphasis on the crucial function of differential conjugated side chain. Finally, the future opportunities and challenges of the J-series polymers in PSCs are discussed.
Flexible Electrochromic Poly(thiophene-furan) Film via Electrodeposition with High Stability
Wen-Qian Yao, Pei-Pei Liu, Wei-Qiang Zhou, Xue-Min Duan, Jing-Kun Xu, Jia-Ji Yang, Shou-Li Ming, Meng Li, Feng-Xing Jiang
Corrected proof , doi: 10.1007/s10118-021-2501-7
[Abstract](204) [FullText HTML](76) [PDF 2543KB](0)
Flexible electrochromic (EC) materials have an urgent demand in the current electronic equipment market due to their technological interest and applications. However, at present, few flexible EC devices developed by industry exist due to some problems and challenges still to be solved such as flexibility. In this work, we have successfully synthesized a novel thiophene-furan (TFu) monomer via Stille coupling reaction, and facilely electrochemically polymerized in a neutral Bu4NPF6-CH2Cl2 electrolyte system to afford the corresponding poly(thiophene-furan) (PTFu) polymer film with good flexibility. The electrochemical and photoelectrochemical analyses of the as-prepared PTFu demonstrate that it has achieved the improved EC performance compared with pure polyfuran and polythiophene polymers, and as a result it possesses favorable EC parameters manifested as a reasonable ΔT (32.1%), faster response (1.38 s), excellent coloration efficiency (CE, 300.9 cm2·C−1), and after a continuous redox process up to 2000 s, its optical stability can be maintained at 96%, and even after 3000 s, it can still be maintained at 80%. In addition, the successful assembly of the electrochromic device of PTFu film can easily realize the reversible conversion of the color from orange to gray. All these systematic studies suggest that the as-prepared flexible PTFu film is a promising candidate for EC materials and has great potential interest for versatile EC applications.
Preparation and Characterization of Attractive Poly(amino acid) Hydrogels Based on 2-Ureido-4[1H]-Pyrimidinone
Zhen Shi, Qi Wang, Gui-Fei Li, Yu-Feng Shou, Hong-Jie Zong, Shi-Feng Yan, Kun-Xi Zhang, Jing-Bo Yin
Corrected proof , doi: 10.1007/s10118-021-2498-y
[Abstract](263) [FullText HTML](79) [PDF 2004KB](0)
Self-healing hydrogels with the shear-thinning property are novel injectable materials and are superior to traditional injectable hydrogels. The self-healing hydrogels based on 2-ureido-4[1H]-pyrimidinone (UPy) have recently received extensive attention due to their dynamic reversibility of UPy dimerization. However, generally, UPy-based self-healing hydrogels exhibit poor stability, cannot degrade in vivo and can hardly be excreted from the body, which considerably limit their bio-application. Here, using poly(l-glutamic acid) (PLGA) as biodegradable matrix, branching α-hydroxy-ω-amino poly(ethylene oxide) (HAPEO) as bridging molecule to introduce UPy, and ethyl acrylate polyethylene glycol (MAPEG) to introduce double bond, the hydrogel precursors (PMHU) are prepared. A library of the self-healing hydrogels has been achieved with well self-healable and shear-thinning properties. With the increase of MAPEG grafting ratio, the storage modulus of the self-healing hydrogels decreases. The self-healing hydrogels are stable in solution only for 6 h, hard to meet the requirements of tissue regeneration. Consequently, ultraviolet (UV) photo-crosslinking is involved to obtain the dual crosslinking hydrogels with enhanced mechanical properties and stability. When MAPEG grafting ratio is 35.5%, the dual crosslinking hydrogels can maintain the shape in phosphate-buffered saline solution (PBS) for at least 8 days. Loading with adipose-derived stem cell spheroids, the self-healing hydrogels are injected and self-heal to a whole, and then they are crosslinked in situ via UV-irradiation, obtaining the dual crosslinking hydrogels/cell spheroids complex with cell viability of 86.7%±6.0%, which demonstrates excellent injectability, subcutaneous gelatinization, and biocompatibility of hydrogels as cell carriers. The novel PMHU hydrogels crosslinked by quadruple hydrogen bonding and then dual photo-crosslinking of double bond are expected to be applied for minimal invasive surgery or therapies in tissue engineering.
Facile Mechanochemical Preparation of Polyamide-derivatives via Solid-state Benzoxazine-isocyanide Chemistry
Xu Sun, Wei Shi, Xin-Yu Zhou, Sheng Ding
Corrected proof , doi: 10.1007/s10118-021-2510-6
[Abstract](208) [FullText HTML](80) [PDF 1071KB](0)
With the exploration of novel sustainable protocol for functional polyamides’ (PAs) construction as the starting point, herein, the small molecular model compound (M1-ssBIC) was prepared firstly by manual grinding of monofunctional benzoxazine (1a) and isocyanide (1b) via solid-state benzoxazine-isocyanide chemistry (ssBIC) to evaluate the feasibility of ssBIC. Linear PAs (P1-series polymers) were subsequently synthesized from biunctional benzoxazine (2a) and isocyanide (2b), and the influence of the loading of catalyst (octylphosphonic acid) (OPA) on the polymerization was investigated. Afterwards, two kinds of cross-linked PAs were successfully constructed via ssBIC by using trifunctional benzoxazine (3a) and cross-linked polybenzoxazine (4a) as reaction substrates, respectively, thus verifying the adaptability of ssBIC. Structural characterization indicates that amide, phenolic hydroxyl and tertiary amine substructures, with metal-complexing capability, have been successfully integrated into the obtained PAs. A type of representative PA/silver composite (P3-AgNPs) was prepared subsequently via in situ reduction treatment, and its application as recyclable reduction catalyst for organic pollutant p-nitrophenol (4-NP) was preliminarily investigated here to provide the example for possible downstream application of ssBIC. We think that this current work could provide a new pathway for the construction of functional PAs through facile and sustainable ssBIC protocol.
An Ultrasensitive, Durable and Stretchable Strain Sensor with Crack-wrinkle Structure for Human Motion Monitoring
Ze-Yu Li, Wei Zhai, Yun-Fei Yu, Guo-Jie Li, Peng-Fei Zhan, Jian-Wei Xu, Guo-Qiang Zheng, Kun Dai, Chun-Tai Liu, Chang-Yu Shen
Corrected proof , doi: 10.1007/s10118-021-2500-8
[Abstract](262) [FullText HTML](83) [PDF 5675KB](4)
Flexible strain sensor has promising features in successful application of health monitoring, electronic skins and smart robotics, etc. Here, we report an ultrasensitive strain sensor with a novel crack-wrinkle structure (CWS) based on graphite nanoplates (GNPs)/thermoplastic urethane (TPU)/polydimethylsiloxane (PDMS) nanocomposite. The CWS is constructed by pressing and dragging GNP layer on TPU substrate, followed by encapsulating with PDMS as a protective layer. On the basis of the area statistics, the ratio of the crack and wrinkle structures accounts for 31.8% and 9.5%, respectively. When the sensor is stretched, the cracks fracture, the wrinkles could reduce the unrecoverable destruction of cracks, resulting in an excellent recoverability and stability. Based on introduction of the designed CWS in the sensor, the hysteresis effect is limited effectively. The CWS sensor possesses a satisfactory sensitivity (GF = 750 under 24% strain), an ultralow detectable limit (strain = 0.1%) and a short respond time of 90 ms. For the sensing service behaviors, the CWS sensor exhibits an ultrahigh durability (high stability > 2×104 stretching-releasing cycles). The excellent practicality of CWS sensor is demonstrated through various human motion tests, including vigorous exercises of various joint bending, and subtle motions of phonation, facial movements and wrist pulse. The present CWS sensor shows great developing potential in the field of cost-effective, portable and high-performance electronic skins.
Scalable Reaction-spinning of Rigid-rod Upilex-S® Type Polyimide Fiber with an Ultrahigh Tg
Sen-Sen Zheng, Han Dong, Shi-Hua Wang, Jie Dong, Tao Guo, Xin Zhao, Qing-Hua Zhang
Corrected proof , doi: 10.1007/s10118-021-2508-0
[Abstract](129) [FullText HTML](93) [PDF 0KB](0)
In the family of polyimide (PI) materials, Upilex-S® film has been a shining star through the research PI materials due to its appealing merits. Unfortunately, the wholly rigid-rod backbone and easily formed skin-core micromorphology and microvoids of Upilex-S® type PI lead to the high difficulty in melt- and wet-spinning fabrication. Herein, we propose a facile and scalable method, reaction-spinning, to fabricate the Upilex-S® type PI fiber, in which the rapid solidification of spinning dope and partial imidization take place simultaneously. Thus, the stability and mechanical strength of as-spun fibers can be improved, and the microvoids in fibers can be greatly reduced in relative to the wet-spun fibers. The resultant Upilex-S® type PI fiber shows higher tensile strength and modulus than most commercial thermal-oxidative polymeric fibers with an ultrahigh glass transition temperature Tg of 478 °C. Moreover, the WAXS and SAXS results indicate that orthorhombic crystals are formed for Upilex-S® type PI fiber in the post hot-drawing process. Increasing the hot-drawing temperature results in a continuous crystallization and high orientation of PI chains in amorphous phase and perfects the existing lamellar structure, which make a great contribution to the improved mechanical property.
Structural Changes and Electrodynamic Effects in Polymers under Fast Uniaxial Compression
Aleksey. I. Aleksandrov, Ivan A. Aleksandrov, Vitaliy G. Shevchenko, Aleksandr N. Ozerin
Corrected proof , doi: 10.1007/s10118-021-2511-5
[Abstract](165) [FullText HTML](80) [PDF 722KB](0)
Rheological explosion in polymers under uniaxial compression in an open volume occurs at the end of continuous rapid plastic deformation after several stages of creep. Two types of polymers were chosen for this study: brittle glassy amorphous polystyrene and thermoplastic semi-crystalline polypropylene. Electric pulses were detected during explosion, and their spectra were analyzed with two models. X-ray diffraction methods were used to investigate changes in the structure and morphology of polymers during deformation and rheological explosion. The pores appear in polymer in this process, and their shape and size distribution were derived from X-ray experiments. The main reason for the formation of pores in polymer samples in rheological explosion experiments is the intense microshifts in the polymer volume under the action of high applied pressure.
The Relationship between Pendant Phosphate Groups and Mechanical Properties of Polyisoprene Rubber
Shi-Qi Li, Mao-Zhu Tang, Cheng Huang, Rong Zhang, Guang-Su Huang, Yun-Xiang Xu
Corrected proof , doi: 10.1007/s10118-021-2497-z
[Abstract](135) [FullText HTML](62) [PDF 0KB](0)
It is still a great challenge to mimic the structure and function of natural rubber by introducing polar components into synthetic polyisoprene. In order to explore the function of phosphate groups on the mechanical properties of polyisoprene rubber, a terminally functionalized compound (PIP-P) containing phosphate groups was synthesized and further vulcanized to prepare the model compound V-PIP-P. Through analyzing the test results, it was found that these phosphate groups formed polar aggregates in non-polar polyisoprene rubber matrix, serving as an additional dynamic cross-linking sites, which increases the cross-linking density and improves mechanical properties. The influence of the phosphate groups on the strain-induced crystallization (SIC) was further investigated via synchrotron wide-angle X-ray diffraction (WAXD) experiment. These phosphate group aggregates not only reduced the onset strain of SIC, but also slowed down the molecular chain mobility, which hinder the crystal lateral growth. The above results help us to gain a deeper understanding for the function of phosphate groups in the formation of “naturally occurring network” and guide the molecular design of next generation polyisoprene rubber.
Azobenzene Based Photo-responsive Mechanical Actuator Fabricated by Intermolecular H-bond Interaction
Chun-Yan Yu, Jia-Hui Mu, Yun-Lei Fu, Yun-Chao Zhang, Ji-Shu Han, Rui-Yang Zhao, Jia Zhao, Zi-Hao Wang, Zhong-Cheng Zhao, Wei-Jun Li, Fu-Sheng Liu
Corrected proof , doi: 10.1007/s10118-021-2504-4
[Abstract](271) [FullText HTML](91) [PDF 629KB](0)
Photo-responsive mechanical actuator is a class of stimuli-responsive materials transferring light to mechanical energy through macroscopic transformation. To fabricate photo-responsive mechanical actuator, soft polymeric materials crosslinked with functional bridging structures are desired. Supramolecular interaction is a relatively common way to fabricate crosslinked materials due to its excellent self-assembly performance. And azobenzene and derivatives are ideal candidates of photo-responsive materials because of the unique photo-induced trans-cis isomerization. Here, a new kind of crosslinked materials based on supramolecular interaction between 4,4'-dihydroxyazobenzene and chitosan is reported. Under 355 nm irradiation, the macroscopic bending of polymeric materials occurs rapidly due to the photo-isomerization of 4,4'-dihydroxyazobenzene. Meanwhile, the photo-responsive mechanical actuator can also lift weight which is up to 200 times that of the actuator itself, and convert energy from light to mechanical work efficiently. This report suggests a new kind of photo-responsive actuator based on supramolecular interaction and may be helpful to contribute a theoretical basis to the design and synthesis of photo-responsive mechanical actuator suitable for large-scale manufacturing industrialization in future.
Temperature-dependent Crystallization and Phase Transition of Poly(L-lactic acid)/CO2 Complex Crystals
Ying Zheng, Cai-Liang Zhang, Yong-Zhong Bao, Guo-Rong Shan, Peng-Ju Pan
Corrected proof , doi: 10.1007/s10118-021-2502-6
[Abstract](219) [FullText HTML](88) [PDF 712KB](0)
Semicrystalline polymers can crystallize in the unique crystalline polymorph and show different phase behaviors under the high-pressure CO2 treatment. Understanding such unique crystallization and phase transition behavior is of fundamental importance for the CO2-assisited processing of semicrystalline polymers. Herein, we investigated the polymorphic crystalline structure, phase transition, and structure-property relationships of poly(L-lactic acid) (PLLA) treated by CO2 at different pressures (1−13 MPa) and crystallization temperatures (Tc’s, 10−110 °C). PLLA crystallized in the PLLA/CO2 complex crystals under 7−13 MPa CO2 at Tc ≤ 50 °C but the common α crystals under the high-pressure CO2 at Tc ≥ 70 °C. Solid-state nuclear magnetic resonance analysis indicated that the PLLA/CO2 complex crystals possessed weaker interactions between the PLLA chains than the common α crystals. The PLLA/CO2 complex crystals were metastable and transformed into the thermally stable α crystals via the solid-to-solid route during heating or annealing at the temperature above 50 °C. The complex crystals of PLLA produced at low Tc was more ductile than the α crystals due to the lower crystallinity and the plasticizing effect of CO2.
Dynamic Bonds Mediate π-π Interaction via Phase Locking Effect for Enhanced Heat Resistant Thermoplastic Polyurethane
Yue Lai, Xiao Kuang, Wen-Hong Yang, Yu Wang, Ping Zhu, Jing-Pu Li, Xia Dong, Du-Jin Wang
Corrected proof , doi: 10.1007/s10118-020-2494-7
[Abstract](263) [FullText HTML](75) [PDF 1130KB](0)
Stimulus-responsive polymers containing dynamic bonds enable fascinating properties of self-healing, recycling and reprocessing due to enhanced relaxation of polymer chain/network with labile linkages. Here, we study the structure and properties of a new type of thermoplastic polyurethanes (TPUs) with trapped dynamic covalent bonds in the hard-phase domain and report the frustrated relaxation of TPUs containing weak dynamic bond and π-π interaction in hard segments. As detected by rheometry, the aromatic TPUs with alkyl disulfide in the hard segments possess the maximum network relaxation time in contrast to those without dynamic bonds and alicyclic TPUs. In situ FTIR and small-angle scattering results reveal that the alkyl disulfide facilitates stronger intermolecular interaction and more stable micro-phase morphology in π-π interaction based aromatic TPUs. Molecular dynamics simulation for pure hard segments of model molecules verify that the presence of disulfide bonds leads to stronger π-π stacking of aromatic rings due to both enhanced assembling thermodynamics and kinetics. The enhanced π-π packing and micro-phase structure in TPUs further kinetically immobilize the dynamic bond. This kinetically interlocking between the weak dynamic bonds and strong molecular interaction in hard segments leads to much slower network relaxation of TPU. This work provides a new insight in tuning the network relaxation and heat resistance as well as molecular self-assembly in stimulus-responsive dynamic polymers by both molecular design and micro-phase control toward the functional applications of advanced materials.
Thienylmethylene Oxindole Based Conjugated Polymers via Direct Arylation Polymerization and Their Electrochromic Properties
Wei Yang, Hao-Guo Yue, Dong Zhao, Hui Yan, Kang-Li Cao, Jin-Sheng Zhao, Qing Zhang
Corrected proof , doi: 10.1007/s10118-021-2503-5
[Abstract](237) [FullText HTML](66) [PDF 687KB](1)
Direct arylation methods have been used to polymerize thienylmethylene oxindoles (TEIs) and 3,3-bis[[(2-ethylhexyl)oxy]methyl]-3,4-dihydro-2H-thieno-[3,4-b][1,4]dioxepin (ProDOT) for new donor-acceptor conjugated polymers. The polymers exhibited blue hues in neutral-state with distinct color-to-transmissive reversible electrochromic switching under applied potentials from 0 V to +1.5 V, and showed high coloration efficiencies (436−438 cm2·C−1) in near-infrared regions with high switching speeds around 1−2 s under ambient conditions.
Computer Simulation Study on Adsorption and Conformation of Polymer Chains Driven by External Force
He-Bei Gao, Hong Li, Xiao-Qin Zhang, Xiang-Hong Wang, Chao-Yang Li, Meng-Bo Luo
Corrected proof , doi: 10.1007/s10118-020-2491-x
[Abstract](176) [FullText HTML](77) [PDF 882KB](0)
In this work, Monte Carlo simulations are used to study the critical adsorption behaviors of flexible polymer chains under the action of an external driving force F parallel to an attractive flat surface. The critical adsorption temperature Tc decreases linearly with increasing F, indicating that the driving force suppresses the adsorption of polymer. The conformation of polymer is also affected by the driving force. However, the effect of F is dependent on the competition between the driving force and temperature. Under strong force or at low temperature, the polymer is stretched along the direction of the force, while under weak force or at high temperature, the polymer is not stretched. When the force is comparable to the temperature, the polymer may be stretched perpendicular to the driving force, and below Tc, we observe conformational transitions from parallel to perpendicular and again to parallel by decreasing the temperature. We found that the perpendicular stretched conformation leads the polymer chain to synchronously move along the direction of the driving force. Moreover, the conformational transitions are attributed to the competition and cooperation between the driving force and the temperature.
Effect of Interfacial Adsorption on the Stability of Thin Polymer Films in a Solvent-induced Process
Lin Xu, Tong-Fei Shi, Li-Jia An, Yu-Yuan Lu, Li-Na Wang
Corrected proof , doi: 10.1007/s10118-020-2493-8
[Abstract](222) [FullText HTML](61) [PDF 854KB](0)
The stability of ultrathin polymer films plays a crucial role in their technological applications. Here, we systematically investigated the influence of interfacial adsorption in physical aging and the stability of thin polymer films in the solvent-induced process. We further identify the stability mechanism from the theory of thin film stability. Our results show that the aging temperature and film thickness can strongly influence the stability of thin PS films in acetone vapor. Physical aging can greatly improve the stability of thin polymer films when the aging temperature Taging1 > Tg. A thinner PS film more quickly reaches a stable state via physical aging. At short aging time, the formation of the adsorbed layer can reduce the polar interaction; however, it slightly influences the stability of thin polymer films in the solvent-induced process. At later aging stage, the conformational rearrangement of the polymer chains induced by the interfacial effect at the aging temperature Taging1 plays an important role in stabilizing the thin polymer films. However, at Taging2 < Tg, the process of physical aging slightly influences the stability of the thin polymer films. The formation of the adsorbed layer at Taging2 can reduce the short-range polar interaction of the thin film system and cannot suppress the instability of thin polymer films in the solvent-induced process. These results provide further insight into the stable mechanism of thin polymer films in the solvent-induced process.
A Potential Alternative to Polystyrene: Ring-opening Terpolymerization of Different Epoxides with Phthalic Anhydride Using Metal-free Dual Catalysts
Li-Miao Lin, Yong-Hang Xu, Man Shen, Jia-Xin Liang, Shuan-Jin Wang, Min Xiao, Yue-Zhong Meng
Corrected proof , doi: 10.1007/s10118-020-2495-6
[Abstract](257) [FullText HTML](65) [PDF 890KB](0)
A series of semi-aromatic polyesters named as Poly(PO-CHO-PA) were facilely synthesized via ring-opening terpolymerization of bio-based cyclohexane oxide (CHO)/propylene oxide (PO)/phthalic anhydride (PA) using economical U1/PPNCl as dual catalyst. The proportion of CHO-PA and PO-PA segments in polymer can be readily altered by changing the feed ratio of CHO/PO because the reactivity ratios of CHO and PO with PA calculated by Fineman-Ross method are comparable. All synthesized amorphous polyesters with various compositions show one Tg ranging from 62 °C to 133 °C. Significantly, the mechanical, thermal and barrier properties of these amorphous semi-aromatic polyesters are also adjustable and investigated for the first time. The results indicate the semi-polyesters exhibit superior thermostability (T5% ranging from 306 °C to 323 °C) and high tensile strength (40.21−55.7 MPa) that is comparable with polystyrene (PS). Furthermore, Poly(PO-CHO-PA) films possess a promising prospect as packaging materials because of its colorless and highly transparent nature, along with low oxygen and water vapor transmission rate. All above performances may guarantee its potential alternative to commercial PS.
Stress-Structure Relationship of the Reversible Associating Polymer Network under Start-up Shear Flow
Ai-Qing Liu, Li-Jun Liu, Wen-Sheng Xu, Xiao-Lei Xu, Ji-Zhong Chen, Li-Jia An
Corrected proof , doi: 10.1007/s10118-020-2487-6
[Abstract](307) [FullText HTML](67) [PDF 673KB](2)
We adopt Langevin dynamics to explore the stress-structure relationship of telechelic reversible associating polymer gel during start-up shear flow, with shear strengths varying from Wi = 12.6 to Wi = 12640. At weak shear flow Wi = 12.6, the shear stress proportionally increases with shear strain at short times, followed by a strain hardening behavior and then passes through a maximum (σmax, γmax) and finally decreases until it reaches the steady state. During the evolution of stress, the gel network is only slightly broken and essentially maintains its framework, and the strain hardening behavior originates from the excessive stretching of chains. On the other hand, the stress-strain curve at intermediate shear flow Wi = 505.6 shows two differences from that at Wi = 12.6, namely, the absence of strain hardening and a dramatic increase of stress at large strains, which is caused by the rupture of gel network at small strains and the network recovery at large strains, respectively. Finally, at very strong shear flow Wi = 6319.7, the gel network is immediately broken by shear flow and the stress-strain curve exhibits similar behaviors to those of classical polymeric liquids.
Combined Molecular Dynamics Simulation and Rouse Model Analysis of Static and Dynamic Properties of Unentangled Polymer Melts with Different Chain Architectures
Pu Yao, Lu-Kun Feng, Hong-Xia Guo
Corrected proof , doi: 10.1007/s10118-020-2489-4
[Abstract](274) [FullText HTML](69) [PDF 801KB](0)
Chain architecture effect on static and dynamic properties of unentangled polymers is explored by molecular dynamics simulation and Rouse mode analysis based on graph theory. For open chains, although they generally obey ideal scaling in chain dimensions, local structure exhibits nonideal behavior due to the incomplete excluded volume (EV) screening, the reduced mean square internal distance (MSID) can be well described by Wittmer’ theory for linear chains and the resulting chain swelling is architecture dependent, i.e., the more branches a bit stronger swelling. For rings, unlike open chains they are compact in term of global sizes. Due to EV effect and nonconcatenated constraints their local structure exhibits a quite different non-Gaussian behavior from open chains, i.e., reduced MSID curves do not collapse to a single master curve and fail to converge to a chain-length-independent constant, which makes the direct application of Wittmer’s theory to rings quite questionable. Deviation from ideality is further evidenced by limited applicability of Rouse prediction to mode amplitude and relaxation time at high modes as well as the non-constant and mode-dependent scaled Rouse mode amplitudes, while the latter is architecture-dependent and even molecular weight dependent for rings. The chain relaxation time is architecture-dependent, but the same scaling dependence on chain dimensions does hold for all studied architectures. Despite mode orthogonality at static state, the role of cross-correlation in orientation relaxation increases with time and the time-dependent coupling parameter rises faster for rings than open chains even at short time scales it is lower for rings.
A Self-supporting, Surface Carbonized Filter Paper Membrane for Efficient Water-in-Oil Emulsion Separation
Jiang-Yong-Quan Cao, Si-Chong Chen, Jie Zhang, Yang-Yang Xie, Yu-Zhong Wang
Corrected proof , doi: 10.1007/s10118-020-2492-9
[Abstract](281) [FullText HTML](67) [PDF 950KB](0)
Due to the important role of oil source in our life, the separation of water-in-oil emulsion is urgent and necessary. Membrane seperation technology has been an efficient and widely used method in separating oil-water separation. Herein, we report a versatile approach to fabricate surface carbonized membranes with self-standing property from biomass-derived precursor by synergistic charring of phytic acid, arginine and filter paper. The obtained membrane exhibited superhydrophobicity in oil, excellent fouling resistance, and self-supporting ability. The membrane can be cycle-used at least 12 times with high permeation flux (up to 1380 L·m−2·h−1) and separation efficiency (up to 99.4%).
Side-chains Engineering of Conjugated Polymers toward Additive-free Non-fullerene Organic Solar Cells
Feng Liu, Dan Wang, Jun-Yu Li, Cheng-Yi Xiao, Yong-Gang Wu, Wei-Wei Li, Guang-Sheng Fu
Corrected proof , doi: 10.1007/s10118-020-2490-y
[Abstract](248) [FullText HTML](64) [PDF 2976KB](0)
Side-chain engineering plays a significant role in the design of conjugated materials. In this work, a series of conjugated polymers PBDB-T-R with functionalized groups at the end of side units were developed as electron donor for organic solar cells (OSCs). The donor polymers PBDB-T-I and PBDB-T-OAc with iodine and acetate end groups exhibited similar absorption and energy levels, but showed much improved PCEs in OSCs compared to the polymer PBDB-T-H without substitutions at the end groups. Additionally, we found that PBDB-T-I and PBDB-T-OAc based cells exhibited optimized performance when using chloroform as solution-processed solvent without any additives. These results indicate that these conjugated polymers can act as self-additive to fabricate photoactive layers via solution process in OSCs.
Effect of the Nanoparticle Functionalization on the Cavitation and Crazing Process in the Polymer Nanocomposites
Yan-Long Luo, Tian-Tian Li, Bin Li, Xian-Ling Chen, Zhen-Yang Luo, Yang-Yang Gao, Li-Qun Zhang
Corrected proof , doi: 10.1007/s10118-020-2488-5
[Abstract](320) [FullText HTML](71) [PDF 2322KB](0)
The nanoparticle (NP) functionalization is an effective method for enhancing their compatibility with polymer which can influence the fracture property of the polymer nanocomposites (PNCs). This work aims to further understand the cavitation and crazing process, hoping to uncover the fracture mechanism on the molecular level. By adopting a coarse-grained molecular dynamics simulation, the fracture energy of PNCs first increases and then decreases with increasing the NP functionalization degree \begin{document}$ \alpha $\end{document} while it shows a continuous increase with increasing the interaction \begin{document}$ {{\varepsilon }_{\rm{pA}}}$\end{document} between polymer and modified beads. The bond orientation degree is first characterized which is referred to as the elongation. Meanwhile, the stress by polymer chains is gradually reduced with increasing the \begin{document}$ \alpha $\end{document} or the \begin{document}$ {{\varepsilon }_{\rm{pA}}}$\end{document} while that by NPs is enhanced. Furthermore, the percentage of stress by polymer chains first increases and then decreases with increasing the strain while that by NPs shows a contrast trend. Moreover, the number of voids is quantified which first increases and then decreases with increasing the strain which reflects their nucleation and coalescence process. The voids prefer to generate from the polymer-NP interface to the polymer matrix with increasing \begin{document}$ \alpha $\end{document} or \begin{document}$ {{\varepsilon }_{\rm{pA}}}$\end{document}. As a result, the number of voids first increases and then decreases with increasing \begin{document}$ \alpha $\end{document} while it continuously declines with the \begin{document}$ {{\varepsilon }_{\rm{pA}}}$\end{document}. In summary, our work provides a clear understanding on how the NP functionalization influences the cavitation and crazing process during the fracture process.
Super Strong and Tough Elastomers Enabled by Sacrificial Segregated Network
Yong Zhu, Lai-Yun Wei, Xuan Fu, Jun-Qi Zhang, Ling-Min Kong, Guang-Su Huang, Jin-Rong Wu
Corrected proof , doi: 10.1007/s10118-020-2484-9
[Abstract](308) [FullText HTML](87) [PDF 646KB](0)
The integration of high strength and toughness concurrently is a vital requirement for elastomers from the perspective of long-term durability and reliability. Unfortunately, these properties are generally conflicting in artificial materials. In the present work, we propose a facile strategy to simultaneously toughen and strengthen elastomers by constructing 3D segregated filler network via a simple latex mixing method. The as-fabricated elastomers are featured by a microscopic 3D interconnected segregated network of rigid graphene oxide (GO) nanosheets and a continuous soft matrix of sulfur vulcanized natural rubber (NR). We demonstrate that the interconnected segregated filler network ruptures preferentially upon deformation, and thus is more efficient in energy dissipation than the dispersed filler network. Therefore, the segregated filler network exhibits better reinforcing effects for the rubber matrix. Moreover, the excellent energy dissipating ability also contributes to the outstanding crack growth resistance through the release of concentrated stress at the crack tip. As a result, the strength, toughness and fatigue resistance of the nanocomposites are concurrently enhanced. The methodology in this work is facile and universally applicable, which may provide new insights into the design of elastomers with both extraordinary static and dynamic mechanical performance for practical applications.
How the Aggregates Determine Bound Rubber Models in Silicone Rubber? A Contrast Matching Neutron Scattering Study
Li-Zhao Huang, Yue Shui, Wei Chen, Zhong-Ming Li, Hong-Tao Song, Guang-Ai Sun, Jia-Zhuang Xu, Gan-Ji Zhong, Dong Liu
Corrected proof , doi: 10.1007/s10118-020-2485-8
[Abstract](289) [FullText HTML](81) [PDF 917KB](0)
The correlation between aggregates and bound rubber structures in silicone rubbers (S(phr)) with various silica fractions (ΦSi) has been investigated by contrast matching small-angle neutron scattering (SANS), swelling kinetics, and low-field nuclear magnetic resonance (NMR). Mixed solvents with deuterated cyclohexane fractions of 4.9% and 53.7% were chosen to match the scattering length densities of the matrix (SMP(phr)) and the filler (SMS(phr)), respectively. All the data consistently suggest that: (i) There is a critical threshold ΦSic between 10 and 30 phr; below ΦSic, the isolated aggregates are dominant, while beyond ΦSic, some rubber fraction is trapped among the agglomerate; (ii) ΦSi-independent thicknesses around 7.5 nm (NMR) and 8.6 nm (SANS) suggest that the bound rubber formation is determined by inherent properties of the components, and the power-law around 4.2 suggests an exponential changed gradient density of the bound rubber; (iii) SMS(80) presents a bicontinuous bound rubber with three characteristic lengths of 41, 100, and 234 nm. The expanded correlation length, a 20 nm smaller aggregate sizes suggest that such existent bicontinuous network in dry samples with less ΦSi is kind of impacted by swelling. With the obtained bound rubber models, the reinforcing mechanism of filled silicone rubber is elucidated.
Platinum Atoms Dispersed in Single-chain Polymer Nanoparticles
Zhi-Yu Hu, Hong-Ting Pu, Jian-Guo Wu
Corrected proof , doi: 10.1007/s10118-021-2499-x
[Abstract](252) [FullText HTML](57) [PDF 748KB](0)
The intramolecular cross-linking of single polymer chains can form single-chain nanoparticles (SCNPs), which have many applications. In this study, styrenic copolymers with pendent triphenylphosphine as the coordination site for platinum ions (Pt(II)) and benzocyclobutene as the latent reactive groups are synthesized. Triphenylphosphine groups in the chains can coordinate Pt(II) and aid slight single-chain folding in dilute solution. The intramolecular cross-linking caused by the ring-open reaction of benzocyclobutene completes the single-chain collapse and forms stable SCNPs in dilute solution. Pt(II) embedded in SCNPs can be further reduced to platinum atoms (Pt(0)). Pt(0) steadily and atomically dispersed in SCNPs exhibits better catalytic properties than normal polymer carried platinum particles do for the reduction of p-nitrophenol to p-aminophenol.
The Effect of Branching Structure on the Properties of Entangled or Non-covalently Crosslinked Polyisoprene
Mo-Kun Chen, Rong Zhang, Mao-Zhu Tang, Guang-Su Huang, Yun-Xiang Xu
Corrected proof , doi: 10.1007/s10118-020-2480-0
[Abstract](397) [FullText HTML](76) [PDF 815KB](1)
The branching structures in natural rubber (NR) were believed to be critical for its superior mechanical properties. However, it is challenging to unravel the branching structure-function relationship of NR due to the complexity of the system. Herein, polyisoprene-(polyisoprene-g-polylactide) (PI-PLA) as model compound containing branching structure was designed and synthesized, which can improve the modulus, strength and viscoelasticity activation energy compared to those of the pristine polyisoprene (PI). The reason is that the branching structure contributes to the entanglement between polyisoprene chains. In order to probe the effect of branching structure on noncovalently crosslinked system, the polyisoprene block of PI-PLA was epoxidized and mixed with Fe3+ ions to introduce coordination bonds. Compared with the linear counterpart, the branching structure obviously enhanced activation energy of coordinated polyisoprenes, remarkably improving the mechanical properies of elastomer.
Conductive Film with Flexible and Stretchable Capability for Sensor Application and Stealth Information Transmission
Yi-Fei Shan, Kun Yang, Zhi-Xi Li, Xiao-Xiao Wang, Hao Li, Yong-Yan Cui
Corrected proof , doi: 10.1007/s10118-020-2483-x
[Abstract](341) [FullText HTML](73) [PDF 2098KB](0)
Flexible and wearable strain sensors for human-computer interaction, health monitoring, and soft robotics have drawn widespread attention to promising applications in the next generation of artificial intelligence devices. However, conventional semiconductor sensors are difficult to meet the requirements of flexibility and stretchability. Here, we reported a kind of novel and simple sensor based on layer-by-layer (LBL) method. Carbon nanotubes (CNTs) layer provides high ductility and stability in the process of tension sensing, while silver layer provides low initial resistance and fast reflecting in the process of tension sensing. LBL method ensures the uniformity of the conductive layer. The sensor has superior sheet resistance of 9.44 Ω/sq., high elongation at break of 104%. For sensing capability, the sensor has wide reflecting range of 60%, high gauge factor (GF) of 1000 up to 60% strain, fast reflecting time of 165 ms. Excellent reliability and stability have also been verified. It is also worth mentioning that the entire process does not require any expensive equipments, complicated processes or harsh experimental conditions. The above features provide an idea for large-scale application of flexible stretchable sensors.
Facile Adjusting for Cells of Lightweight Isocyanate-based Polyimide Foam and Operable Combination between Different Distinctive Acoustic Foams for Higher Performance
Xiao-He Ren, Gao-Hui Sun, Lei-Chao Wang, Rong-Rong Chen, Jun Wang, Shi-Hui Han
Corrected proof , doi: 10.1007/s10118-020-2482-y
[Abstract](298) [FullText HTML](117) [PDF 1549KB](2)
New ambient sound absorption material, lightweight isocyanate-based polyimide foam (IBPIF), was fabricated by operable combination between different distinctive acoustic IBPIF. Cellular structure of IBPIF was facilely and obviously adjusted by increased slurry temperature corresponding to change in distinctive acoustic properties. Moreover, density of all IBPIF kept at only 12−17 kg/m3. With increasing slurry temperature from 0 °C to 40 °C, cell size and window opening rate gradually increased from 553 μm to 791 μm and from 6.85% to 58.46%, respectively. In this study, IBPIF generated by slurries at 0 °C (marked as PIF-2) and 40 °C (marked as PIF-6) showed best and distinctive acoustic behavior in 315−800 Hz and 800−6300 Hz regions, respectively. After acoustic behavior study of combined IBPIF prepared by stitching combination between two distinctive acoustic IBPIFs, results showed that only when PIF-6 sheet used as sound receiving surface even though with thickness of only 10 mm could the combined IBPIF possess the best acoustic level in 800−6300 Hz region as PIF-6. Furtherly, acoustic behavior in 315−800 Hz region could be significantly enhanced by increasing thickness of PIF-2 and could reach or close to the best acoustic level.
An Interfacial Dynamic Crosslinking Approach toward Catalyst-free and Mechanically Robust Elastomeric Vitrimer with a Segregated Structure
Yong Zhu, Jing-Li Gao, Lin-Jun Zhang, Yan Peng, Hao Wang, Fang-Wei Ling, Guang-Su Huang, Jin-Rong Wu
Corrected proof , doi: 10.1007/s10118-020-2479-6
[Abstract](381) [FullText HTML](143) [PDF 1915KB](2)
Elastomeric vitrimers with covalent adaptable networks are promising candidates to overcome the intrinsic drawbacks of conventional covalently-crosslinked elastomers; however, most elastomeric vitrimers show poor mechanical properties and require the addition of exogenous catalysts. Herein, we fabricate a catalyst-free and mechanically robust elastomeric vitrimer by constructing a segregated structure of sodium alginate (SA) in the continuous matrix of epoxidized natural rubber (ENR), and further crosslinking the composite by exchangeable hydroxyl ester bonds at the ENR-SA interfaces. The manufacturing process of the elastomeric vitrimer is facile and environmentally friendly without hazardous solvents or exogenous catalysts, as the abundant hydroxyl groups of the segregated SA phase can act as catalyst to activate the crosslinking reaction and promote the dynamic transesterification reaction. Interestingly, the segregated SA structure bears most of the load owing to its high modulus and small deformability, and thus ruptures preferentially upon deformation, leading to efficient energy dissipation. Moreover, the periodic stiffness fluctuation between rigid segregated SA phase and soft ENR matrix is beneficial to the crack-resisting. As a result, the elastomeric vitrimer manifests exceptional combination of catalyst-free, defect-tolerance, high tensile strength and toughness. In addition, the elastomeric vitrimer also exhibits multi-shape memory behavior which may further broaden its applications.
Polyarylene Ether Nitrile and Titanium Dioxide Hybrids as Thermal Resistant Dielectrics
Ren-Bo Wei, Chen-Hao Zhan, Yang Yang, Peng-Lin He, Xiao-Bo Liu
Corrected proof , doi: 10.1007/s10118-020-2481-z
[Abstract](264) [FullText HTML](112) [PDF 4369KB](1)
With the expanding application of capacitors, thermal resistant dielectric materials are in high demand due to the increasing harsh environments where the capacitors are needed and the heat generated by the capacitors. Herein, we present polyarylene ether nitrile and titanium dioxide hybrids which can be used as thermal resistant dielectrics for these capacitors. Phthalonitrile modified titanium dioxide (TiO2-CN) and phthalonitrile end-capped polyarylene ether nitrile (PEN-Ph) are firstly prepared. After being cast into TiO2-CN/PEN nanocomposite films, these composites self-crosslink upon heating at 320 °C for 4 h, forming the polyarylene ether nitrile and titanium dioxide hybrids (TiO2-PEN). Improved dielectric constants which are stable from room temperature to 200 °C of these hybrids are observed, indicating the potential application of the hybrids as thermal resistant dielectrics.
Effect of Different Shear Modes on Morphology and Mechanical Properties of Polypropylene Pipes Produced by Rotational Shear
Wei-Chen Zhou, Zu-Chen Du, Hao Yang, Jun-Jie Li, Ying Zhang, Xue-Qin Gao, Qiang Fu
Corrected proof , doi: 10.1007/s10118-020-2477-8
[Abstract](286) [FullText HTML](93) [PDF 2427KB](0)
Oriented “shish-kebab” structures could be obtained by shearing to enhance the mechanical properties of polymer samples markedly. However, the effect of shear mode on mechanical properties is still uncertain. The study of stepped hoop shear field on the isotactic polypropylene (iPP) pipe was developed through applying a self-designed rotational shear system (RSS). The effect of stepped shear field on the microstructure and comprehensive properties of iPP pipe was investigated by the comparison with continuous shear. It could be found that the loosely-assembled shish-kebabs with the larger size were formed in the continuous shear pipes, but the smaller and tightly-stacked ones existed in the pipes with stepped shear. Surprisingly, due to differential morphologies under different shear modes, better comprehensive mechanical properties were obtained in the pipes with stepped shear.
Enhanced Reproducibility of Positive Temperature Coefficient Effect of CB/HDPE/PVDF Composites with the Addition of Ionic Liquid
Long Chen, Xiao Wu, Xiao-Fang Zhang, Jian-Ming Zhang
Corrected proof , doi: 10.1007/s10118-020-2475-x
[Abstract](324) [FullText HTML](90) [PDF 6609KB](3)
Developing an effective method for improving the reproducibility of positive temperature coefficient (PTC) effect is of great significance for large-scale application of polymer based PTC composites, owing to its contribution to the security and reliability. Herein, we developed a carbon black (CB)/high density polyethylene (HDPE)/poly(vinylidene fluoride) (PVDF) composite with outstanding PTC reproducibility, by incorporating 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIm][NTf2]) into the composite. After multiple repeated temperature cycles, the PTC performance of as-prepared material keeps almost unchanged and the varition of resistance at room temperature is less than 7%. Our studies revealed that [OMIm][NTf2] contributes to the improvement of PTC reproducibility in two ways: (i) it acts as an efficient plasticizer for refining the co-continuous phase morphology of HDPE/PVDE blends; (ii) it inhibits the crystallization of PVDF through the dilution effect, leading to more overlaps of the volume shrinkage process of HDPE and PVDF melt which results in the decrease of interface gap between HDPE and PVDF. This study demonstrated that ionic liquids as the multifunctional agents have great potential for improving the reproducibility in the application of the binary polymer based PTC composites.
Melting Temperature of Individual Electrospun Poly(vinylidene fluoride) Fibers Studied by AFM-based Local Thermal Analysis
Ze-Qian Wang, Zhen-Xing Zhong, Yu-Ying Ma, Xiao-Feng Lu, Ce Wang, Zhao-Hui Su
Corrected proof , doi: 10.1007/s10118-020-2476-9
[Abstract](351) [FullText HTML](98) [PDF 1551KB](0)
Thermal properties such as melting temperature can well reflect the microstructure of the polymer material, and have practical implications in the application of nanofibers. In this work, we investigated the melting temperature of individual electrospun poly(vinylidene fluoride) (PVDF) nanofibers with diameters ranging from smaller than 200 nm to greater than 2 μm by the local thermal analysis technique. The PVDF fibers obtained under four different conditions were found to crystallize into α and β phases, and the fiber mats showed typical values in the crystallinity and Tm with no significant difference among the four. However, analyses at single fiber level revealed broad distribution in diameter and Tm for the fibers produced under identical electrospinning condition. The Tm of individual nanofibers was found to remain constant at large diameters and increase quickly when reducing the fiber diameter toward the nanoscale, and Tm values of 220−230 °C were observed for the thinnest nanofibers, much higher than the typical values reported for bulk PVDF. The Tm and molecular orientation at different positions along a beaded fiber were analyzed, showing a similar distribution pattern with a minimum at the bead center and higher values when moving toward both directions. The results indicate that molecular orientation is the driving mechanism for the observed correlation between the Tm and the diameter of the nanofibers.
Polymerization Kinetics of Propylene with the MgCl2-Supported Ziegler-Natta Catalysts—Active Centers with Different Tacticity and Fragmentation of the Catalyst
Wei-Ping Zheng, Ya-Ping Ma, Da-Lin Du, Ai-Hua He, Hua-Feng Shao, Chen-Guang Liu
Corrected proof , doi: 10.1007/s10118-020-2473-z
[Abstract](423) [FullText HTML](111) [PDF 3811KB](7)
The catalytic activity and stereospecificity of olefin polymerization by using heterogeneous TiCl4/MgCl2 Ziegler-Natta (Z-N) catalysts are determined by the structure and nature of active centers, which are mysterious and fairly controversial. In this work, the propylene polymerization kinetics under different polymerization temperatures by using Z-N catalysts were investigated through monitoring the concentration of active centers [C*] with different tacticity. SEM was applied to characterize the catalyst morphologies and growing polypropylene (PP) particles. The lamellar thickness and crystallizability of PP obtained under different polymerization conditions were analyzed by DSC and SAXS. The PP fractions and active centers with different tacticity were obtained with solvent extraction fractionation method. The catalytic activity, active centers with different tacticity and propagation rate constant kp, fragmentation of the catalyst, crystalline structure of PP are correlated with temperature and time for propylene polymerizations. The polymerization temperature and time show complex influences on the propylene polymerization. The higher polymerization temperature (60 °C) resulted higher activity, kp and lower [C*], and the isotactic active centers Ci* as the majority ones producing the highest isotactic polypropylene (iPP) components showed much higher kp when compared with the active centers with lower stereoselectivity. Appropriate polymerization time provided full fragmentation of the catalyst and minimum diffusion limitation. This work aims to elucidate the formation and evolution of active centers with different tacticity under different polymerization temperature and time and its relations with the fragmentation of the PP/catalyst particles, and provide the solutions to the improvement of catalyst activity and isotacticity of PP.
Structure and Properties of Isotactic Polypropylene/Polybutene-1 In-reactor Alloys
Ya-Ping Ma, Ning Zhang, Wei-Ping Zheng, Ai-Hua He, Chen-Guang Liu
Corrected proof , doi: 10.1007/s10118-020-2468-9
[Abstract](642) [FullText HTML](103) [PDF 896KB](19)
The composition and structure of polymer largely determine the properties of its final products. As a novel polymer material, the composition, structure, and properties of the isotactic polypropylene/polybutene-1 in-reactor alloy (iPP/iPB alloy) synthesized by sequential two-stage polymerization with Ziegler-Natta catalyst were correlated for the first time in this work. The iPP/iPB alloy was fractionated by temperature rising elution fractionation (TREF) in a broad temperature ranged from –30 °C to 140 °C, and the chain microstructures and sequence distributions of isolated fractions were analyzed by DSC, GPC, 13C-NMR, and FTIR. The iPP/iPB alloy was composed of five components, namely high isotactic PB (iPB, 85.8 wt%), medium isotactic PB (mPB, 5.1 wt%), poly((butene-1)-block-propylene) copolymers (PB-b-PP, 4.1 wt%) which contained PB and PP blocks with different lengths according to the isolation temperature, isotactic PP (iPP, 2.7 wt%), and atactic PB (aPB, 2.3 wt%). Compared to other commercial pipe materials, the iPP/iPB alloy presented outstanding thermal creep resistance and gas permeability resistance, high strength and low deformation at high temperature, and appropriate flexural strength. The roles of PP and PB-b-PP components in the alloy were interpreted. This work is expected to elucidate the potential application of iPP/iPB alloy as pipe materials and provide solutions for the design and synthesis of high performance pipe materials.
Advanced Surfaces by Anchoring Thin Hydrogel Layers of Functional Polymers
Farzad Seidi, Wei-Feng Zhao, Hui-Ning Xiao, Yong-Can Jin, Mohammad Reza Saeb, Chang-Sheng Zhao
Corrected proof , doi: 10.1007/s10118-020-2474-y
[Abstract](315) [FullText HTML](113) [PDF 1364KB](8)
Surface design and engineering is a critical tool to improve the interaction of materials with their surroundings. Immobilization of soft hydrogels is one of the attractive strategies to achieve surface modification. The goal of this review is to provide a comprehensive overview of the different strategies used for surface tethering of hydrogel layers via crosslinking immobilization of pre-fabricated functional polymers. In this strategy, crosslinkable polymers are first prepared via various polymerization techniques or post-functionalization of polymers. Afterwards, the crosslinkable polymers are attached or tethered on the surfaces of substrates using a variety of approaches including photo-crosslinking, click reactions, reversible linkages, etc. For each case, the principles of hydrogel tethering have been explained in detail with representative examples. Moreover, the potential applications of the as-modified substrates in specific cases have also been addressed and overviewed.
Texture Induced by Molecular Weight Dispersity: Polymorphism within Poly(L-lactic acid) Spherulites
Da-Peng Hu, Min Chen, Yu-Hui Yang, Han-Ying Li
Corrected proof , doi: 10.1007/s10118-020-2464-0
[Abstract](516) [FullText HTML](107) [PDF 1970KB](6)
Poly(L-lactic acid) (PLLA) has drawn much attention due to its excellent medical and pharmaceutical applications for decades. As a semi-crystalline polymer, morphology and crystal structure of PLLA greatly determine its properties. Here, we demonstrate, for PLLA films, a non-conventional texture featuring two types of spherulites emerging in pairs to form a distinct nested structure where a small spherulite (~10 μm) is embedded in a large one (100 μm to 300 μm). In addition to the size, the molecular weight and polymorph are different in the large and small spherulites. Crystallographic α-form and relatively low molecular weight are identified in the large spherulites, while meta-stable α′-form and relatively high molecular weight in the small ones. These differences suggest that the polydisperse PLLA polymers fractionate during film formation and the high-molecular-weight fraction crystallizes into the small spherulites with meta-stable structure because of its complicated polymer entanglement and high viscosity. In contrast, the rest of polymers crystallize into the large spherulites with the thermodynamically stable polymorph. Furthermore, this texture exhibits accelerated PLLA degradation initiated from the small spherulites, which is distinct from the typical PLLA spherulites. Insights provided by this work may lead to new texture-properties relationship associated with polydispersity of molecular weight.
Advantage of Preserving Bi-orientation Structure of Isotactic Polypropylene through Die Drawing
Dong Lyu, Ying-Ying Sun, Yu-Qing Lai, Glen Thompson, Philip Caton-Rose, Phil Coates, Ying Lu, Yong-Feng Men
Corrected proof , doi: 10.1007/s10118-020-2465-z
[Abstract](369) [FullText HTML](99) [PDF 3754KB](12)
The isotactic polypropylene (iPP) usually shows a unique parent-daughter lamellae structure in which the parent and daughter lamellae are against each other with a near perpendicular angle (80° or 100°). Inducing a high fraction of oriented cross-hatched structure in iPP during processing is desirable for designing the bi-oriented iPP products. We processed a commercial iPP via tensile-stretching and die-drawing to evaluate the structural evolution of oriented parent-daughter lamellae. It turned out that the die-drawing process had an advantage in attaining a high fraction of oriented cross-hatched structure of iPP, as compared to the free tensile stretching. Besides, the presence of α-nucleating agents affected the formation of oriented parent-daughter lamellae in the die-drawn samples whereas such influence diminished in the free stretched ones. It was found that the confined deformation inside the die led to the well-preserved oriented cross-hatched structure in the die-drawn iPP.
Enhancing the Crystallization Performance of Poly(L-lactide) by Intramolecular Hybridizing with Tunable Self-assembly-type Oxalamide Segments
Man-Man Yu, Wei-Jun Yang, De-Yu Niu, Xiao-Xia Cai, Yun-Xuan Weng, Wei-Fu Dong, Ming-Qing Chen, Peng-Wu Xu, Yang Wang, Hong Chu, Pi-Ming Ma
Corrected proof , doi: 10.1007/s10118-020-2461-3
[Abstract](351) [FullText HTML](87) [PDF 1861KB](10)
In this work, hydroxyl-terminated oxalamide compounds N1,N2-bis(2-hydroxyethyl)oxalamide (OXA1) and N1,N1-(ethane-1,2-diyl)bis(N2-(2-hydroxyethyl)oxalamide (OXA2) were synthesized to initiate the ring-opening polymerization of L-lactide for preparation of oxalamide-hybridized poly(L-lactide) (PLAOXA), i.e., PLAOXA1 and PLAOXA2. The crystallization properties of PLA were improved by the self-assembly of the oxalamide segments in PLAOXA which served as the initial heterogeneous nuclei. The crystal growth kinetics was studied by Hoffman-Lauritzen theory and it revealed that the nucleation energy barrier of PLAOXA1 and PLAOXA2 was lower than that of PLA. Consequently, PLAOXA could crystallize much faster than PLA, accompanied with a decrease in spherulite size and half-life crystallization time by 74.8% and 86.5% (T = 125 °C), respectively. In addition, the final crystallinity of PLAOXA1 and PLAOXA2 was 6 and 8 times higher, respectively, in comparison with that of neat PLA under a controlled cooling rate of 10 °C/min. The results demonstrate that the hybridization of oxalamide segments in PLA backbone will serve as the self-heteronucleation for promoting the crystallization rate. The higher the content of oxalamide segments (PLAOXA2 compared with PLAOXA1) is, the stronger the promotion effect will be. Therefore, this study may provide a universal approach by hybridizing macromolecular structure to facilitate the crystallization of semi-crystalline polymer materials.
Tuning the Electrically Conductive Network of Grafted Nanoparticles in Polymer Nanocomposites by the Shear Field
Yan-Long Luo, Xiao-Hui Duan, Bin Li, Xian-Ling Chen, Yang-Yang Gao, Li-Qun Zhang
Corrected proof , doi: 10.1007/s10118-020-2467-x
[Abstract](552) [FullText HTML](118) [PDF 692KB](15)
Controlling the formation of the conductive network in the polymer nanocomposites (PNCs) is very meaningful to enhance their electrical property. In this work, we investigated the effect of grafted nanoparticles (NPs) on the conductive probability of PNCs in the quiescent state as well as under the shear field via a coarse-grained molecular dynamics simulation. It is found that the smallest percolation threshold is realized at the moderate grafting density, the moderate length of grafted chains or the moderate interaction between grafted chains and free chains. Corresponding to it, the dispersion state of NPs varies from the contact aggregation to the uniform dispersion. By analyzing the connection mode among NPs, the probability of NPs which connect three other ones reaches the maximum value at their moderate dispersion state which is responsible for the optimal conductive probability. In addition, the main cluster size is characterized to better understand the conductive network which is consistent with the percolation threshold. It is interesting to find that the percolation threshold is smaller under the shear field than under the quiescent state. The shear field induces more NPs which connect three other ones. This benefits the formation of the new conductive network. Meanwhile, the anisotropy of the conductive probability is reduced with increasing the grafting density. In summary, this work provides a clear picture on how the conductive network of grafted NPs evolves under the shear field.
Copolymer-assisted Polypropylene Separator for Fast and Uniform Lithium Ion Transport in Lithium-ion Batteries
Yan Yan, Qing-Ran Kong, Chuang-Chao Sun, Jia-Jia Yuan, Zheng Huang, Li-Feng Fang, Bao-Ku Zhu, You-Zhi Song
Corrected proof , doi: 10.1007/s10118-020-2455-1
[Abstract](450) [FullText HTML](113) [PDF 1311KB](6)
In lithium-ion batteries (LIBs), separators play a vital role in lithium-ion (Li+) transport, and thus affect rate performance, battery life, and safety. Here, a new kind of multifunctional copolymer poly(acrylonitrile-co-lithium acrylate-co-butyl acrylate) (PAAB-Li) is synthesized through soap-free emulsion polymerization, and is used to form homogeneous-covered separator based on PP matrix by a simple dip-annealing process. Compared to the bare PP separator, the modified separators with PAAB-Li enable higher ionic conductivity, higher lithium ion transference number (increased from 0.360 to 0.525), and lower interface impedance (reduced from 155 Ω to 34 Ω). It has been indicated that PAAB-Li functional layer significantly promotes the fast transport of Li+ and improves the compatibility of the separator/electrolyte-electrode interface. The LiCoO2/graphite cells with the PAAB-Li-assisted separator demonstrate excellent cycle stability and rate performance. In addition, the Li symmetric cells with the modified separator stably cycle over 800 h, indicating the functional layer effectively suppresses the lithium dendrite growth. This facile strategy can be easily applied to LIBs requiring high safety and even be scalable to Li metal batteries. Moreover, the possible mechanism of the PAAB-Li functional layer promoting fast and uniform Li+ transport is discussed in this paper.
Effect of Chain Configuration on Thermal Conductivity of Polyethylene—A Molecular Dynamic Simulation Study
Xiang Zhang, Yu Wang, Ru Xia, Bin Wu, Peng Chen, Jia-Sheng Qian, Hao-Jun Liang
Corrected proof , doi: 10.1007/s10118-020-2466-y
[Abstract](422) [FullText HTML](127) [PDF 675KB](7)
Stretched polyethylene (PE) fibers are found to have super high thermal conductivity, while the bulk of polyethylene is usually thermal insulating even for those with high crystalline degree. A molecular dynamic simulation is deliberately carried out to examine the relationship between chain configuration and thermal conductivity of polyethylene. In this simulation study, independent and interacting PE chains being stretched are compared with the aim to find out the effect of stretching on thermal conductivity of PE. Various crystallization conditions for PE bulk are considered. It is found that heat transports predominately along the covalent chain rather than across chains in PE crystals. Our simulation study helps to understand experimental findings on thermal conductivity of PE at different states. We also predict that amorphous PE may be super thermally conductive if chains are strictly stretched along heat flux.
Highly Cis-1,4 Selective Polymerization of Conjugated Dienes Catalyzed by N-heterocyclic Carbene-ligated Neodymium Complexes
Shu Zhang, Na Wu, Yi-Xian Wu
Corrected proof , doi: 10.1007/s10118-020-2460-4
[Abstract](407) [FullText HTML](113) [PDF 425KB](7)
Neodymium complexes containing N-heterocyclic carbene (NHC) ligands, NdCl3[1,3-R2(NCH=)2C:]·THFx ( Nd1 : R = 2,6-iPr2C6H3, x = 0; Nd2 : R = 2,6-Et2C6H3, x = 1; Nd3 : R = 2,4,6-Me3C6H2, x = 1) were synthesized and employed as precatalysts for the coordination polymerization of conjugated dienes (butadiene and isoprene). In combination with triisobutylaluminium (TIBA), Nd1 promoted butadiene polymerization to produce extremely high cis-1,4 (up to 99.0%) polybutadienes with high molecular weight (Mw = 250−780 kg·mol−1). The Nd1 /TIBA catalytic system also exhibited both high catalytic activity and cis-1,4 selectivity (up to 97.8%) for isoprene polymerization. The catalytic activity, molecular weight and molecular weight distribution of resulting polydienes were directly influenced by Al/Nd molar ratio, aging method, and polymerization temperature. Very interestingly, the high cis-1,4 selectivity of the catalyst towards butadiene and isoprene kept almost unchanged under different reaction conditions. The cis-1,4 polyisoprenes with high molecular weight (Mw = 210−530 kg·mol−1) and narrow molecular weight distribution (Mw/Mn = 1.9−2.7) as well as high cis-1,4 selectivity (~97%) could be synthesized by using the aged Nd1 /TIBA catalytic system in the presence of isoprene (100 equivalent to Nd) at low Al/Nd molar ratios of 6−10. Polyisoprenes with low molecular weights (Mw = 12−76 kg·mol−1) and narrow molecular weight distributions (Mw/Mn = 1.7−2.6) were obtained by using Nd2 and Nd3 as precatalysts, indicating that the molecular weight of resulting polyisoprenes can be adjusted by changing the substitutes of ligand in Nd complex.
Controllably Growing Topologies in One-shot RAFT Polymerization via Macro-latent Monomer Strategy
Liu-Qiao Zhang, Yang Gao, Zhi-Hao Huang, Wei Zhang, Nian-Chen Zhou, Zheng-Biao Zhang, Xiu-Lin Zhu
Corrected proof , doi: 10.1007/s10118-020-2463-1
[Abstract](503) [FullText HTML](117) [PDF 781KB](11)
The controlled and efficient synthesis of polymers with tailored topologies is challenging but important for exploring structure/property research. Herein, we proposed a concept of macro-latent monomer to achieve the controlled growth of polymer topologies. The macro-latent monomer was installed by a dynamic furan/maleimide covalent bond at the chain terminal. One-shot reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene and the macro-latent monomer created controlled growth of polymer topologies. Low temperature such as 40 °C could not activate the macro-latent monomer and thus the polymerization created the homo-polystyrene. By contrast, high temperature of ~110 °C activated the macro-latent monomer, and a maleimide-terminated macro-monomer was released via the retro-Diels Alder reaction. This macro-monomer immediately joined the cross polymerization with styrene and thus produced the side chains. By delicately manipulating the polymerization temperature, the predetermined placement of the macro-latent monomer-derived polymeric side-chains created controllably growing topologies, including star-, π-shaped, and density-variable grafting copolymers. This work paved a new way for creating on-demand topologies and would greatly enrich the topology synthesis.
Top-down Approach for Fabrication of Polymer Microspheres by Interfacial Engineering
Yue Fan, De-Hui Wang, Jin-Long Yang, Jia-Ning Song, Xiao-Mei Li, Cheng-Lin Zhang, Dong-Sheng Wang, Long-Quan Chen, Jia-Xi Cui, Xu Deng
Corrected proof , doi: 10.1007/s10118-020-2453-3
[Abstract](417) [FullText HTML](244) [PDF 20458KB](12)
Polymer microspheres with uniform size, composition, and surface property have gained extensive researches in past decades. Conventional bottom-up approaches are using monomers or oligomers to build up desired polymer microspheres. However, directly shaping high-molecular-weight polymers into well-ordered polymer microspheres remains a great challenge. Herein, we reported a facile and efficient top-down approach to fabricate microspheres with high-molecular-weight polymer microfibers. By harnessing interfacial engineering-control during the polymer microspheres formation, uniformly sized microspheres could be produced with widely ranged diameters (from 10 μm to the capillary length of each polymer melt). The size limitation of this approach could be further extended by a controllable Plateau-Rayleigh instability phenomenon. Principally, the top-down approach allows fabrication of microspheres by various polymer melts with surface energy higher than 25 mN/m. Our work paves a way for green, cost-effective, and customizable production of a variety of functional polymer microspheres without any chemical reaction assistant.
Insights into the Payne Effect of Carbon Black Filled Styrene-butadiene Rubber Compounds
An Zhao, Xuan-Yu Shi, Shi-Hao Sun, Hai-Mo Zhang, Min Zuo, Yi-Hu Song, Qiang Zheng
Corrected proof , doi: 10.1007/s10118-020-2462-2
[Abstract](404) [FullText HTML](145) [PDF 981KB](5)
As a widely used reinforcing filler of rubber, carbon black (CB) often enhances the nonlinear Payne effect and its mechanism still remains controversial. We adopt simultaneous measurement of rheological and electrical behaviors for styrene-butadiene rubber (SBR)/CB compounds and CB gel (CBG) during large deformation/recovery to investigate the contribution of conductive CB network evolution to the Payne effect of the compounds. In the highly filled compounds, the frequency dependence of their strain softening behavior is much more remarkable than that of their CB network breakdown during loading, while during unloading the unrecoverable filler network hardly affects the complete recovery of modulus, both revealing that their Payne effect should be dominated by the disentanglement of SBR matrix. Furthermore, the bound rubber adjacent to CB particles can accelerate the reconstruction of continuous CB network and improve the reversibility of Payne effect. This may provide new insights into the effect of filler network, bound rubber, and free rubber on the Payne effect of CB filled SBR compounds.
Green Monomer of CO2 and Alkyne-based Four-component Tandem Polymerization toward Regio- and Stereoregular Poly(aminoacrylate)s
Bo Song, An-Jun Qin, Ben Zhong Tang
Corrected proof , doi: 10.1007/s10118-020-2454-2
[Abstract](512) [FullText HTML](131) [PDF 567KB](14)
Green monomers, such as carbon dioxide (CO2), are closely related to our daily life and highly desirable to be transferred to functional polymers with diverse structures and versatile properties because they are abundant, cheap, nontoxic, renewable, and sustainable. However, the polymerizations based on these green monomers are to be further developed. In this work, a facile CO2 and alkyne-based one-pot, two-step, four-component tandem polymerization was successfully established. The polymerization of CO2, diynes, alkyl dihalides, and primary/secondary amines can proceed under mild reaction conditions and regio- and stereoregular poly(aminoacrylate)s with good solubility and thermal stability were obtained in high yields (up to 95%). Notably, distinctly different stereoregularity of resultant poly(aminoacrylate)s was realized via using primary or secondary amines. Using the former would readily generate polymers with 100% Z-isomers, whereas the latter furnished products with over 95% E-isomers. Through different monomer combination, the polymers with tunable structures and properties were obtained. Moreover, the tetraphenylethene units containing poly(aminoacrylate)s, showing the unique aggregation-induced emission characteristics, could function as a fluorescent probe for sensitive explosive detection. Thus, this work not only develops a facile CO2 and alkyne-based multicomponent tandem polymerization but also provides a valuable strategy to fine-tune the polymer structures and properties, which could be potentially applied in diverse areas.
Structural Evolution of LLDPE-LMW/HMW Blend during Uniaxial Deformation as Revealed by In Situ Synchrotron Radiation X-ray Scattering
Pin-Zhang Chen, Hao-Yuan Zhao, Zhi-Jie Xia, Qian-Lei Zhang, Dao-Liang Wang, Ling-Pu Meng, Wei Chen
Corrected proof , doi: 10.1007/s10118-020-2458-y
[Abstract](569) [FullText HTML](171) [PDF 1059KB](17)
The structural evolutions of LLDPE-LMW/HMW blend during uniaxial deformation at temperatures of 80 and 120 °C were investigated by the in situ synchrotron radiation small- and wide-angle X-ray scattering (SR-SAXS/WAXS). The magic sandwich echo (MSE) sequence was used to detect a virtually dead-time-free induction decay (FID) for solid-state NMR analysis. The thermal property of the blend was first checked by DSC, and the temperature dependence of the overall crystallinity was obtained by MSE-FID. The onset melting temperature is determined to be 116 °C (DSC), and the enhanced π-flip motions in the crystalline domains are clearly observed at T > 60 °C by MSE-FID. For deformation at 80 °C, the lamellae become staggered in the strain-softening region as shown by the four-point SAXS pattern, whereas further deformation leads to the melting-recrystallization in the strain-hardening region. For deformation at 120 °C, the six-point SR-SAXS signal appears just after the four-point SR-SAXS signal, which indicates the formation of new lamellae along deformation direction. In addition, no phase transition occurs in the whole deformation process at both temperatures. Current work shows the detailed temperature dependence microstructural evolution of LLDPE-LMW/HMW blend. This is expected to provide more structural information for correlating microscopic structure with macroscopic mechanical performance.
Transparency of Temperature-responsive Shape-memory Gels Tuned by a Competition between Crystallization and Glass Transition
You-Hao Wang, Jin Gong, Wen-Bing Hu
Corrected proof , doi: 10.1007/s10118-020-2456-0
[Abstract](846) [FullText HTML](147) [PDF 1110KB](34)
Transparency is often an important property in the practical applications of temperature-responsive shape-memory gels. We investigated the mechanism of significant transparency improvement upon a change in two copolymer gels with their molar ratios between stearyl acrylate and N,N-dimethylacrylamide from 1:1 to 0.75:1. By means of Flash DSC measurement, we made the thermal analysis characterization of crystallization and glass transition in two copolymer gels and compared the results to the parallel experiments of corresponding homopolymers. The results showed that the slightly lower content of stearyl acrylate sequences suppresses crystallization in their side chains due to the chemical confinement of comonomers on copolymer crystallization; meanwhile it shifts up the glass transition temperature of the backbone N,N-dimethylacrylamide sequences. Eventually on cooling, crystallization gives its priority position to glass transition in copolymer gels, resulting in a higher transparency of the gel without losing the shape-memory performance. To confirm the chemical confinement, we further compared the isothermal crystallization kinetics of stearyl acrylate side chains in the copolymer gel to that of their homopolymer. Our observations facilitate the rational design of the temperature-responsive shape-memory gels for the transparency property.
A Near-infrared Non-fullerene Acceptor with Thienopyrrole-expanded Benzo[1,2-b:4,5-b′]dithiophene Core for Polymer Solar Cells
Zhen Chen, Shan-Shan Ma, Kai Zhang, Zhi-Cheng Hu, Qing-Wu Yin, Fei Huang, Yong Cao
Corrected proof , doi: 10.1007/s10118-020-2440-8
[Abstract](617) [FullText HTML](164) [PDF 478KB](24)
A near-infrared non-fullerene acceptor (NFA) BDTIC, based on thienopyrrole-expanded benzo[1,2-b:4,5-b′]dithiophene unit (heptacyclic S,N-heteroacene) as core, is designed and synthesized. The aromatic pyrrole ring with strong electron-donating ability in the core enhances the intramolecular charge transfer effect, finely tunes the optical bandgap and absorption profile of BDTIC, and thus results in a narrowed optical bandgap (\begin{document}$E_{\rm{g}}^{\rm{opt}}$\end{document}) of 1.38 eV and a near-infrared absorption to 900 nm. When BDTIC is paired with donor polymer PBDB-T to fabricate organic solar cells, the optimized device achieves a best power conversion efficiency of 12.1% with a short-circuit current density of 20.0 mA·cm–2 and an open-circuit voltage of 0.88 V. The photovoltaic performance benefits from the broad absorption, weak bimolecular recombination, efficient charge separation and collection, and favorable blend morphology. This work demonstrates that thienopyrrole-expanded benzo[1,2-b:4,5-b′]dithiophene unit (heptacyclic S,N-heteroacene) is a promising building unit to construct high-performance NFAs by enhancing the intramolecular charge transfer effect, broadening absorption as well as maintaining good intermolecular stacking property.
Identifying Conformation States of Polymer through Unsupervised Machine Learning
Li-Wang Sun, Hong Li, Xiao-Qin Zhang, He-Bei Gao, Meng-Bo Luo
Corrected proof , doi: 10.1007/s10118-020-2442-6
[Abstract](853) [FullText HTML](137) [PDF 564KB](22)
The study of the critical behavior is important for classifying different configuration states. Recently, machine learning is capable of discriminating polymer states in the presence of human supervision. Here, we introduce an unsupervised approach based on the self-organizing map (SOM) and the autoencoder network to locate critical phase transitions from raw configuration without the necessity for manual feature engineering. High-dimensional configuration data can be encoded to low-dimensional codes by employing neural network of multilayer restrictive Boltzmann machines and the intermediate code can also be reconstructed to high-dimensional input vector. And then the codes are used to cluster different configuration states for polymers adsorbed on the homogeneous and the stripe-patterned surface by the SOM network and K-Means method. This work presents an unusual tool to identify polymer configuration.
Diffusion of a Ring Threaded on a Linear Chain
Zhen-Hua Wang, Yu-Yuan Lu, Hui Jin, Chuan-Fu Luo, Li-Jia An
Corrected proof , doi: 10.1007/s10118-020-2448-0
[Abstract](439) [FullText HTML](140) [PDF 1224KB](14)
A mesoscopic simulation is applied to investigate the effects of hydrodynamic interactions and axial chains on the dynamics of threaded rings. The hydrodynamic interactions significantly speed up the diffusion and relaxation of both free and threaded rings. The decoupled diffusion and relaxation dynamics indicate the broken of the Einstein-Stokes relationship. The diffusion of a ring threaded on a flexible chain exhibits a synergism effect compared to that on an axial rod, which originates from the self-diffusion of the ring and the reptation-like motion of the axial chain. Meanwhile, hydrodynamic interactions significantly improve the synergism effect, leading to an enhanced sliding motion of the threaded ring. The faster sliding of threaded rings suggests that the entropic barrier is negligible, which agrees well with the basic assumption of barrier-less confining tube at equilibrium in tube theory. Our results provide a new perspective on analysis of the effects of topology constraints on polymer dynamics.
Investigating the Nucleation Effect of DMDBS on Syndiotactic Polypropylene from the Perspective of Chain Conformation
Xin-Xin Wang, Jian-Jun Yi, Li Wang, Yuan Yuan, Jia-Chun Feng
Corrected proof , doi: 10.1007/s10118-020-2447-1
[Abstract](501) [FullText HTML](160) [PDF 695KB](14)
The mechanism of nucleating agents (NAs) accelerating the crystallization of semi-crystalline polymers has received continuous attention due to the extreme importance in academic research and industry application. In this work, the nucleation effect and probable mechanism of 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol (DMDBS) on promoting the crystallization of syndiotactic polypropylene (sPP) was systematically investigated. Our results showed that DMDBS could significantly accelerate the crystallization process and did not change the crystalline form of sPP. The in situ infrared spectra recorded in the crystallization process showed that in pristine sPP the tttt conformers decreased and the ttgg conformers increased subsequently. In sPP/DMDBS system, DMDBS could promote the increase of ttgg conformers rather than the decrease of tttt conformers. The further analysis by 2D-IR spectra revealed that ttgg conformers increased prior to the decrease of tttt conformers in the sPP/DMDBS system comparing with pristine sPP. Considering that ttgg conformers were basic elements of helical conformation of Form I crystal for sPP, we proposed a probable nucleation mechanism of DMDBS for sPP:DMDBS could stabilize the ttgg conformers which induced these ttgg conformers to pre-orientate and aggregate into helical conformation sequences as initial nuclei quickly and early to promote the sPP crystallization. Our work provides some new insights into the nucleation mechanism of NAs for sPP.
Improved Properties of Aromatic Polyamide Tape-casting Films
Fu-Lin Liu, Jian-Jun He, Hai-Xia Yang, Shi-Yong Yang
Corrected proof , doi: 10.1007/s10118-020-2445-3
[Abstract](554) [FullText HTML](208) [PDF 949KB](11)
A convenient tape-casting method was applied to prepare high performance aromatic polyamide (PA) films based on Technora®. During the polycondensation, CaO was introduced to improve the solubility of the PA resin, and the generated halides were totally removed from the film via a simple water bath, without leaving any defects in PA films. The factors of processing temperature and immersion time had been systematically investigated, and the experimental results demonstrated that both of them had impressive impacts on aggregation state and comprehensive properties of the PA film. It was suggested that immersion in water for more than 1 min and baking below 300 °C for 10 min were the optimal conditions for the thermal, tensile, tear, and optical properties to be in the best equilibrium. The resultant PA films integrated outstanding film-forming ability and excellent general performance, especially the tensile property and tear resistance.
Refractive Index Engineering as a Novel Strategy toward Highly Transparent and Tough Sustainable Polymer Blends
Si-Ting Sun, Hang Wang, Dong Huang, Ying-Li Ding, Yang Zhang, Dong-Po Song, Kun-Yu Zhang, Li Pan, Yue-Sheng Li
Corrected proof , doi: 10.1007/s10118-020-2439-1
[Abstract](471) [FullText HTML](179) [PDF 1380KB](18)
High transparency and toughness are prerequisites for sustainable polymers if they are to find wide application as alternatives to petroleum-based polymers. However, the utility of sustainable polymers such as commercially available polylactide (PLA) is limited by their inherent brittleness and high cost. Unfortunately, toughening PLA-based materials via cost-effective blending strategies without sacrificing transparency remains a challenge. Herein, we report a novel strategy involving active refractive index matching for creation of highly transparent and tough PLA blends. Specifically, we engineered the refractive index of a promising renewable poly(epichlorohydrin-co-ethylene oxide) elastomer by introducing polar ionic moieties via a simple chemical method, and we blended the resulting ionomers with PLA. The best blend showed an impact strength of > 80 kJ/m2, an elongation at break of 400%, and high transparency (90%). These characteristics are of great importance for potential applications such as packaging. Our strategy offers a versatile new way to prepare high-performance sustainable polymer materials with excellent transparency.
Origin of High Elastic Recovery of Hard-elastic Polypropylene Film at Room Temperature: the Mixed Contribution of Energy Elasticity and Entropy Elasticity
Jia-Yi Xie, Rui-Jie Xu, Cai-Hong Lei
Corrected proof , doi: 10.1007/s10118-020-2432-8
[Abstract](457) [FullText HTML](175) [PDF 848KB](11)
The crystalline and amorphous regions were alternately arranged in the hard elastic polypropylene (PP) films with row-nucleated lamellae. In this work, their structure evolution during stretching and recovery at room temperature was followed and the elastic recovery mechanism was discussed by twice cyclic tensile experiment. During the first stretching to 100%, the lamellae crystals are parallel separated and the intercrystallite crazing is formed at the first yield point. Many nano-cavities within the intercrystallite crazing appear when the strain reaches 20%. The strain-hardening process accompanies with the lamellae long period increasing and the intercrystallite crazing enlargement. After the secondary yield point, the lamellae cluster is further separated and more nano-cavities appear. The first and second recovery processes are complete overlap. During recovery, firstly, the energy elasticity provided by nano-cavities surface tension drives the shrinkage of material, and then the entropy elasticity related to amorphous chain relaxation plays a leading role when the strain is smaller than the secondary yield point. The elastic recovery process of hard elastic material is the co-contribution of energy elasticity and entropy elasticity. This work gives a clearer recognition about the source of hard elastic property and the role of amorphous region in material’s deformation.
Flame-retardant and Self-healing Biomass Aerogels Based on Electrostatic Assembly
Ji-Yu Yang, Yu Xia, Jin Zhao, Long-Fei Yi, Yong-Jiao Song, Hong Wu, Shao-Yun Guo, Li-Juan Zhao, Jin-Rong Wu
Corrected proof , doi: 10.1007/s10118-020-2444-4
[Abstract](473) [FullText HTML](232) [PDF 1565KB](8)
It remains a significant challenge to fabricate self-healing aerogels with excellent flame retardancy. Herein, we develop a class of biomass aerogels by electrostatically assembling chitosan (CS), phytic acid (PA), and itaconic acid (IA). The electrostatic interaction between CS and IA is weak and dynamic, so freeze-drying the solution of CS and IA enables the formation of continuous aerogel skeleton with self-healing ability and re-programmability; in comparison, the electrostatic interaction between CS and PA is strong and less dynamic, and thus mixing PA with CS in aqueous solution leads to fine precipitates of high flame retardancy due to the synergistic phosphorus-nitrogen effect. Integrating the continuous skeleton and the fine precipitates results in self-healing aerogles with UL-4 V-0 rating of flame retardancy aerogels and auto-extinguishable feature. Interestingly, the aerogels after burning in flame for 30 s form a skin-core structure, and the carbonized skin protects the integrity of the aerogels and the self-healing ability of the internal parts. Therefore, this work provides a facile strategy to develop multi-functional aerogels which hold great promise for advanced applications.
Facile Construction of Synergistic β-Glucosidase and Cellulase Sequential Co-immobilization System for Enhanced Biomass Conversion
Guan Wang, Kai Zhang, Jia-Yi Xin, Chang-Wen Zhao, Yu-Hong Ma, Wan-Tai Yang
Corrected proof , doi: 10.1007/s10118-020-2437-3
[Abstract](499) [FullText HTML](157) [PDF 520KB](9)
Converting renewable cellulose into glucose via cellulase catalysis for further production of biofuel has been recognized as one of the most promising ways for solving energy crisis. However, the hydrolysis performance of immobilized cellulase was not satisfactory for practical application due to the reduced catalytic efficiency and lack of β-glucosidase (BG) component in cellulase. Here, a facile method was developed to sequentially co-immobilize BG and cellulase by polymeric microparticles with hierarchical structure. In this strategy, BG was firstly entrapped into the cross-linked poly(ethylene glycol) (PEG) microparticles via inverse emulsion polymerization initiated by isopropyl thioxanthone (ITX) under the irradiation of visible light, leaving the formed ITX semi-pinacol (ITXSP) dormant groups on surface of BG-loaded microparticles, which could be further activated by visible light irradiation and initiated a graft polymerization to introduce poly(acrylic acid) (PAA) brush on the PEG core. After that, cellulase was covalently bonded on the PAA chains via carbodiimide reaction. The synergic effect of BG and cellulase was verified in the dual enzyme immobilization system, which led to a better stability at a wide range of temperature and pH than free enzymes. The dual enzymes system exhibited excellent reusability, which could retain 75% and 57% of the initial activity after 10 cycles of hydrolysis of carboxyl methyl cellulose and 5 cycles of hydrolysis of filter paper, respectively, indicative of the potential in biofuel areas in a cost-effective manner.
Challenges and Recent Developments of Photoflow-RDRP
Zhuoran Zhong, Yinan Chen, Yang Zhou and Mao Chen
Accepted Manuscript , doi: 10.1007/s10118-021-2529-8
[Abstract](33) [PDF 4247KB](0)
Photo-controlled reversible-deactivation radical polymerization (Photo-RDRP) has been investigated as a “green” and spatiotemporally controlling pathway for polymer synthesis. While the combination of photo-RDRP and flow chemistry has offered opportunities to increase light intensity and enable uniform light irradiation, problems associated with flow approaches are still remained for photoflow-RDRP,which has hindered merging flow polymerization with other cutting-edge techniques. Herein, we summarize challenges and recent achievements in photoflow-RDRP including the development of a) droplet/slug-flow to regulate residence time distribution, b) mixing techniques to tailor polymer, c) polymerization induced self-assembly, and d) computer-aided synthesis. We hope this work will provide informative knowledge to people in related fields and stimulate novel ideas to promote polymer synthesis in both academia and industry.
Melting and annealing peak temperatures of poly(butylene succinate) on the same Hoffman-Weeks plot parallel to Tm = Tc line
Zhi-Ning Xie, Hai-Mu Ye, Tong Chen, Tian-Ze Zheng, Jun Xu, Bao-Hua Guo
Accepted Manuscript , doi: 10.1007/s10118-021-2530-2
[Abstract](14) [PDF 2172KB](0)
The crystallization and melting behavior of polymers is of theoretical importance. In this work, poly(butylene succinate) (PBS) was selected as an example to study such behavior at low supercooling via introduction of the extended-chain crystal (ECC) of the same polymer as nucleating agent. The crystallization of PBS with its ECC as nucleating agent in a wide temperature range (90–127 °C) and the following melting behavior were studied. It is revealed that the melting point (Tm, for Tc ≥ 113 °C) and the annealing peak temperature (Ta, for Tc = 90–100 °C) show similar asymptotic behavior. Both Tm and Ta approach to a value of ca. 3.3 °C higher than the corresponding Tc when the crystallization time tc approaches the starting point. That is to say, the Hoffman-Weeks plot is parallel to Tm = Tc line. The crystallization line became parallel to the melting line when PBS was crystallized at Tc higher than 102 °C. Based on these results, we propose that the parallel relationship and the intrinsic similarity between the Ta and the Tm observed at the two ends of the Tc range could be attributed to the metastable crystals formed at the beginning of crystallization.
Isoselective Ring-opening Polymerization of rac-Lactide Catalyzed by N-Heterocyclic Olefin/(Thio)urea Organocatalysts
Zhenyu Wang, Guangqiang Xu, Li Zhou, Chengdong Lv, Rulin Yang, Bingzhe Dong, Qinggang Wang
Accepted Manuscript , doi: 10.1007/s10118-021-2535-x
[Abstract](0) [PDF 1090KB](0)
The isoselective ring-opening polymerization of rac-lactide was achieved by combining N-heterocyclic olefin (NHO) with mono(thio)ureas or bis(thio)ureas as catalytic systems. The polymerization process shows high stereoselectivity, controllability and reactivity, delivering multi-block isotactic polylactides with high chain-end fidelity and narrow molecular weight distributions. The enhancement of catalytic performance was observed in the following order: bisthiourea (DTU) < monothiourea (TU) < bisurea (DU) < urea (U). The highest Pm = 0.91 was observed at -70 C when using NHO/U1 catalytic system and the high stereoselectivity was attributed to chain-end control mechanism.
Comparison of the structural evolution of β polypropylene during the sequential and simultaneous biaxial stretching process
Daoxin Zhang, Lei Ding, Feng Yang, Fang Lan, Ya Cao, Ming Xiang
Accepted Manuscript , doi: 10.1007/s10118-021-2534-y
[Abstract](0) [PDF 6651KB](0)
In this paper, the lamellar structural evolution and microvoids variations of β-iPP during the processing of two different stretching methods, sequential biaxial stretching and simultaneous biaxial stretching, were investigated in detail. It was found that different stretching methods led to significantly different lamellae deformation modes, and the microporous membranes obtained from the simultaneous biaxial stretching exhibited better mechanical properties. For the sequential biaxial stretching, abundant coarse fibers originated from the tight accumulation of the lamellae parallel to the longitudinal stretching direction, whereas the lamellae perpendicular to the stretching direction were easily deformed and separated. Those coarse fibers were difficult to be separated to form micropores during the subsequent transverse stretching process, resulting in a poor micropores distribution. However, for the simultaneous biaxial stretching, the β crystal had the same deformation mode, that is, the lamellae distributed in different directions were all destroyed, forming abundant microvoids and little coarse fibers formation.
Reversible Mechanochemistry Enabled Autonomous Sustaining of Robustness of Polymers – an Example of Next Generation Self-healing Strategy
Ming-Xuan Li, Min-Zhi Rong, and Ming-Qiu Zhang
Accepted Manuscript , doi: 10.1007/s10118-021-2532-0
[Abstract](26) [PDF 2794KB](0)
Even under low external force, a few macromolecules of a polymer have to be much more highly stressed and fractured first due to the inherent heterogeneous microstructure. When the materials keep on working under loading, as is often the case, the minor damages would add up, endangering the safety of use. Here we show an innovative solution based on mechanochemically initiated reversible cascading variation of metal-ligand complexations. Upon loading, crosslinking density of the proof-of-concept metallopolymer networks autonomously increases, and recovers after unloading. Meanwhile, the stress-induced tiny fracture precursors are blocked to grow and then restored. The entire processes reversibly proceed free of manual intervention and catalyst. The proposed molecular-level internal equilibrium prevention mechanisms fundamentally enhance durability of polymers in service.
Macroscopic regulation of hierarchical nanostructures in liquid-crystalline block copolymers towards functional materials
Feng Cai, Yuxuan Chen, Wenzhong Wang, Haifeng Yu
Accepted Manuscript , doi: 10.1007/s10118-021-2531-1
[Abstract](23) [PDF 4263KB](0)
The great potential of liquid-crystalline block copolymers (LCBCs) containing photoresponsive mesogens toward novel applications in photonics and nanotechnology has been attracting increasing attention, due to the combination of the inherent property of microphase separation of block copolymers and the hierarchically-assembled structures of liquid-crystalline polymers (LCPs). The periodically ordered nanostructures in bulk film of LCBCs can be acquired by supramolecular cooperative motion, derived from the interaction between liquid-crystalline elastic deformation and microphase separation, which are able to improve physical properties of polymer film toward advanced functional applications. Moreover, various micro/nano-patterned structures have been fabricated via light manipulation of photoresponsive LCBCs with good reproducibility and mass production. Thanks to recent developments in synthesis and polymerization techniques, diverse azobenzene-containing LCBCs have been designed, resulting in the creation of a wide variety of novel functions. This review illustrates recent progresses in macroscopic regulation of hierarchical nanostructures in LCBCs towards functional materials. The existing challenges are also discussed, showing perspectives for future studies.
Enzyme-assisted Photoinitiated Polymerization-Induced Self-Assembly in Continuous Flow Reactors with Oxygen Tolerance
Weibin Cai, Dongdong Liu, Ying Chen, Li Zhang, Jianbo Tan
Accepted Manuscript , doi: 10.1007/s10118-021-2533-z
[Abstract](18) [PDF 2495KB](0)
Polymerization-induced self-assembly (PISA) is an emerging method for the preparation of block copolymer nano-objects at high concentrations. However, most PISA formulations have oxygen inhibition problems and inert atmospheres (e.g. argon, nitrogen) are usually required. Moreover, the large-scale preparation of block copolymer nano-objects at room temperature is challenging. Herein, we report an enzyme-assisted photoinitiated polymerization-induced self-assembly (photo-PISA) in continuous flow reactors with oxygen tolerance. The addition glucose oxidase (GOx) and glucose into the reaction mixture can consume oxygen efficiently and constantly, allowing the flow photo-PISA to be performed under open-air conditions. Polymerization kinetics indicated that only a small amount of GOx (0.5 μM) was needed to achieve the oxygen tolerance. Block copolymer nano-objects with different morphologies can be prepared by varying reaction conditions including the DP of core-forming block, monomer concentration, reaction temperature, and solvent composition. We expect this study will provide a facile platform for the large-scale production of block copolymer-nano-objects with different morphologies at room temperature.
Foam/Film Alternating Multilayer Structure with High Toughness and Low Thermal Conductivity Prepared via Microlayer Coextrusion
Qi Luo, Hongting Pu, Zhihua Zhang, Xiong Zhang, and Chenglong Yu
Accepted Manuscript , doi: 10.1007/s10118-021-2524-0
[Abstract](59) [PDF 1630KB](0)
Multilayer membranes prepared via microlayer coextrusion have attracted wide attention due to their unique properties and broad applications. In present study, the foam/film alternating multilayer sheets based on ethylene-vinyl acetate copolymer (EVA) and high-density polyethylene are successfully prepared via microlayer coextrusion. The cells in the sheets are single-cell-array along the foamed EVA layers with uniform cell size. In addition, the effects of layer number and foam relative thickness on morphology, mechanical properties, damping and heat insulation properties are investigated. The cell size decreases significantly with increasing layer number due to the enhanced confine effects. The tensile strength, elongation at break, and heat insulation also increase significantly. However, the mechanical damping properties change little in the observed frequency. Meanwhile, with higher relative thickness of EVA foam, the sheets have lower tensile strength and lower thermal conductivity, while the damping properties are enhanced in a specific frequency scope. The elongation at break of the optimized sample comes to 800% and the thermal conductivity decreases to 61 mW (mk)-1, which shows high toughness and low thermal conductivity, indicating a possible method to prepare materials with high toughness and heat-insulating properties.

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2020, 38(11) .  
[Abstract](93) [FullText HTML](52) [PDF 51566KB](0)
Ultrasmall Nanoparticle ROS Scavengers Based on Polyhedral Oligomeric Silsesquioxanes
Zhan Li, Haotian Li, Jianhua Zhang, Xianhu Liu, Zhipeng Gu, Yiwen Li
2020, 38(11): 1149 -1156.   doi: 10.1007/s10118-020-2486-7
[Abstract](356) [FullText HTML](136) [PDF 647KB](1)
Although tremendous efforts have been devoted to the structural and functional tailoring of natural polyphenol-functionalized nanoparticles, preparing ultrasmall sized (< 6 nm) particles with precisely-defined structures has remained a grand challenge. In this work, we reported the preparation of ultra-small and precisely structured polyhedral oligomeric silsesquioxanes (POSS)-based polyphenol nanoparticles (T8-, T10-, and T12-GAPOSS) by accurately functionalizing the POSS surface with plant polyphenol gallic acid units via thiol-Michael “click” reactions. Those polyphenol nanoparticles exhibited strong free radical scavenging capacity, good biocompatibility and ability to resist cell oxidative damage, which demonstrated great potentials in inhibiting oxidative stress induced pathologies.
High Open-circuit Voltage and Low Voltage Loss in All-polymer Solar Cell with a Poly(coronenediimide-vinylene) Acceptor
Han Han, Fu-Jin Bai, Rong Wei, Han Yu, Yi-Kun Guo, He Yan, Da-Hui Zhao
2020, 38(11): 1157 -1163.   doi: 10.1007/s10118-020-2426-6
[Abstract](507) [FullText HTML](199) [PDF 391KB](15)
Reducing the voltage loss (Vloss) is a critical factor in optimizing the open-circuit voltage (Voc) and overall power-conversion efficiency (PCE) of polymer solar cells. In the current work, by designing a novel electron-accepting unit of coronenediimide (CDI) and using it as the main functional building block, a new polymer acceptor CDI-V is developed and applied to fabricate all-polymer solar cells. Compared with the perylenediimide-based polymer acceptors we previously reported, the current CDI-V polymer possesses a noticeably elevated lowest unoccupied molecular orbital (LUMO). Thereby, by virtue of the enlarged energy gap between the donor HOMO and acceptor LUMO, a high Voc value of 1.05 V is achieved by the all-polymer photovolatic device, along with an impressively low Vloss of 0.55 V. As remarkably, in spite of an extremely small LUMO level offset of 0.01 eV exhibited by the donor and acceptor polymers, effective charge separation still takes place in the all-polymer device, as evidenced by a proper short-circuit current (Jsc) of 9.5 mA·cm−2 and a decent PCE of 4.63%.
Thermoresponsive Nanogels from Dendronized Copolymers for Complexation, Protection and Release of Nucleic Acids
Yi Yao, Jian-Hui Wu, Shi-Jie Cao, Bi-Yi Xu, Jia-Tao Yan, Di Wu, Wen Li, Afang Zhang
2020, 38(11): 1164 -1170.   doi: 10.1007/s10118-020-2452-4
[Abstract](763) [FullText HTML](92) [PDF 7931KB](14)
A series of thermoresponsive cationic dendronized copolymers and their corresponding nanogels containing dendritic oligoethylene glycol (OEG) units and guanidine groups were prepared, and their complexation, protection, and release of nucleic acids were investigated. The dendritic OEGs endow these copolymer materials with good biocompatibility and characteristic thermoresponsiveness, while cationic guanidine groups can efficiently bind with the nucleic acids. The dendritic topology also affords the copolymers specific shielding effect which plays an essential role in protecting the activity of nucleic acids. At room temperature, dendronized copolymers and the corresponding nanogels could efficiently capture and condense the nucleic acids, while above their cloud points (Tcps), more than 75% of siRNA could be released in 1 h triggered by ATP. More importantly, the copolymer showed protective capability to siRNA, while nanogels exhibit even better protection when compared to the copolymers due to the synergetic effect from the three-dimensional cross-linked network and high density of dendritic units in vicinity. This kind of smart dendronized copolymer nanogels form a novel class of scaffolds as promising materials for biomedical applications.
Synthesis of Functional Hyperbranched Poly(methyltriazolylcarboxylate)s by Catalyst-free Click Polymerization of Butynoates and Azides
Mu-Ning Lang, Wei-Wen Chi, Ting Han, Qing-Zhen Zhao, Hong-Kun Li, Ben Zhong Tang, Yong-Fang Li
2020, 38(11): 1171 -1177.   doi: 10.1007/s10118-020-2421-y
[Abstract](475) [FullText HTML](184) [PDF 491KB](17)
Azide-alkyne click polymerization has become a powerful tool for polymer synthesis. However, the click polymerization between internal alkynes and azides is rarely utilized to prepare functional polymers. In this work, the polymerization reactions of activated internal alkyne monomers of tris(2-butynoate)s ( 1 ) with tetraphenylethene-containing diazides ( 2 ) were performed in dimethylformamide (DMF) under simple heating, affording four hyperbranched poly(methyltriazolylcarboxylate)s (hb-PMTCs) with high molecular weights (Mw up to 2.4 × 104) and regioregularities (up to 83.9%) in good yields. The hb-PMTCs are soluble in common organic solvents, and thermally stable with 5% weight loss temperatures up to 400 °C. They are non-emissive in dilute solution, but become highly emissive in aggregated state, exhibiting aggregation-induced emission characteristics. The polymers can generate fluorescent photopatterns with high resolution, and can work as fluorescent sensors to detect nitroaromatic explosive with high sensitivity.
Activation and Deactivation of Chain-transfer Agent in Controlled Radical Polymerization by Oxygen Initiation and Regulation
Chun-Na Lv, Ning Li, Yu-Xuan Du, Jia-Hua Li, Xiang-Cheng Pan
2020, 38(11): 1178 -1184.   doi: 10.1007/s10118-020-2441-7
[Abstract](791) [FullText HTML](204) [PDF 2273KB](58)
The activation and deactivation of the chain-transfer agent were achieved by oxygen initiation and regulation with triethylborane under ambient temperature and atmosphere. The autoxidation of triethylborane overcame the oxygen inhibition and produced initiating radicals that selectively activate the chain-transfer agent for the chain growth or deactivate the active chain-end of polymer in controlled radical polymerization. Both activation and deactivation were highly efficient with broad scope for various polymers with different chain-transfer agents in both organic and aqueous systems. Oxygen molecule was particularly used as an external regulator to initiate and achieve the temporal control of both activation and deactivation by simply feeding the air.
Homeotropic Alignment and Selective Adsorption of Nanoporous Polymer Film Polymerized from Hydrogen-bonded Liquid Crystal
An-Qi Xiao, Xiao-Lin Lyu, Hong-Bing Pan, Zhe-Hao Tang, Wei Zhang, Zhi-Hao Shen, Xing-He Fan
2020, 38(11): 1185 -1191.   doi: 10.1007/s10118-020-2431-9
[Abstract](520) [FullText HTML](196) [PDF 573KB](32)
Nanoporous polymer film with a hexagonal columnar (Colh) structure was fabricated by templated hydrogen-bonding discotic liquid crystals containing methacrylate functional group. The supramolecular hydrogen-bonded complex T3Ph-L is composed of a 1,3,5-tris(1H-benzo[d]imidazol-2-yl)benzene (T3Ph) core molecule as the hydrogen-bonding acceptor and 3,4,5-tris((11-(methacryloyloxy)undecyl)oxy)benzoic acid (L) peripheral molecules as donors. And the Colh structure is always retained after self-assembly, photo-crosslinking, and removal of the template T3Ph. The nanoporous polymer film can retain the Colh phase even under the dry condition, which indicates more possibilities for practical applications. After chemical modification of the inner wall of the nanopores, the nanoporous polymer film with pores of about 1 nm selectively adsorbs ionic dyes, and the adsorption process is spontaneous and exothermic in nature. Homeotropic alignment can be obtained when the blend complex was sandwiched between two modified glasses after annealing by slow cooling, which shows that the nanoporous polymer film has potential in applications such as nanofiltration.
Stereoblock Polypropylenes Prepared by Efficient Chain Shuttling Polymerization of Propylene with Binary Zirconium Catalysts and iBu3Al
Xiao Yin, Huan Gao, Fei Yang, Li Pan, Bin Wang, Zhe Ma, Yue-Sheng Li
2020, 38(11): 1192 -1201.   doi: 10.1007/s10118-020-2446-2
[Abstract](540) [FullText HTML](192) [PDF 522KB](13)
Stereoblock polypropylenes bearing isotactic, atactic, and syndiotactic polypropylene segments were successfully prepared by dry methyl aluminoxane activated binary catalysts system, Ph2CFluCpZrCl2 and {Me2Si(2,5-Me2-3-(2-MePh)-cyclopento[2,3-b]thiophen-6-yl)2}ZrCl2, in the presence of iBu3Al as a chain shuttling agent. By studying the catalyst activity, chain transfer efficiency, and reversibility of chain transfer reaction of each catalyst system, as well as the molecular weight and polydispersity of the resulting polymers, the alkyl exchange reactions between the zirconium catalyst and different main-group metal alky were estimated, respectively. Based on the optimized react condition, the chain shuttling polymerization was conducted by binary catalyst system in the presence of iBu3Al under both atmospheric and high pressure. Resultant polymers were identified as stereoblock polypropylenes according to microstructure and physical properties analyses by 13C{1H}-NMR, DSC, and GPC.
Long-term Thermo-oxidative Degradation Modeling of a Carbon Fiber Reinforced Polyimide Composite: Multistep Degradation Behaviors and Kinetics
Yi Liu, Xiao-Zhou Xu, Song Mo, Bang-Wei Lan, Cai-Zhen Zhu, Cui-Hua Li, Jian Xu, Lin Fan
2020, 38(11): 1202 -1213.   doi: 10.1007/s10118-020-2425-7
[Abstract](653) [FullText HTML](156) [PDF 1191KB](6)
This study aims to disclose the thermo-oxidative degradation behaviors and kinetics of a carbon fiber reinforced polyimide (CFRPI) composite for modeling of the long-term degradation process. The degradation behaviors were revealed through off-gas products analysis, and the overall kinetic interpretation was achieved from study of the mass-loss curves recorded under dynamic conditions. It was found that thermo-oxidative degradation of the CFRPI composite was a multistep process, which included four main reaction steps. Since most kinetic analysis methods were derived from simple reactions described by a single kinetic triplet, they cannot be applied reliably to such a process. Therefore, we firstly separated the four overlapped reaction steps by peak fitting of derivative thermogravimetric curves using Fraser-Suzuki equation considering the asymmetrical nature of kinetic curves, and subsequently analyzed each individual reaction employing Friedman method and experimental master-plots method. Four sets of kinetic triplets were determined to characterize the entire degradation process. The validity of four corresponding kinetic triplets was confirmed by perfect simulation of mass-loss curves recorded at both dynamic conditions used in kinetic analysis and entirely different isothermal conditions. Finally, modeling of long-term aging at 400 °C of the CFRPI composite was successfully achieved based on these kinetic triplets. The predicted mass loss and flexural property correlated well with experimental results. This study can serve as a basis for rapid evaluation of the long-term durability of the CFRPI composite in various application environments.
Thermostable α-Diimine Nickel Complexes with Substituents on Acenaphthequinone-backbone for Ethylene Polymerization
Rui-Fang Zhang, Yan-Hui Hou, Xu-Ling Wei, Ding-Ding Zhao, Mi-Mi Cui, Fei-Fan Zhai, Xiang-Liu Li, Bin-Yuan Liu, Min Yang
2020, 38(11): 1214 -1220.   doi: 10.1007/s10118-020-2430-x
[Abstract](516) [FullText HTML](159) [PDF 397KB](4)
In order to promote the thermostability of α-diimine nickel complex by ligand backbone structure, a series of α-diimine nickel complexes with substituents on acenaphthequinone backbone were synthesized and used as catalysts for ethylene polymerization. When the hydroxyethyl phenoxyl group was introduced to the acenaphthequinone-backbone, the thermal stability and activity of the catalyst could be significantly improved. The catalytic activity of complex C2 [5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-diisopropyl)acenaphthylene-1,2-diimine]nickel(II) dibromide with isopropyl substituents on N-aryl reached 8.2 × 106 g/(molNi·h) at 70 °C and 2 MPa. The activity of [5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-dibenzhydryl-4-menthylphenyl)acenaphthylene-1,2-diimine]nickel(II) dibromide ( C3 ) still maintained at 6.7 × 105 g/(molNi·h) at 120 °C. Compared with C3 containing bulky dibenzhydryl substituents, the activity of C2 was sensitive to the change of the polymerization pressure. However, the polyethylenes obtained from complex C3 had lower branching density. Meanwhile, the molecular weight could reach 971 kg/mol, which is almost 5 times as much as that of the polyethylene obtained from complex C2 .
Highly Stretchable, Compressible, Adhesive, Conductive Self-healing Composite Hydrogels with Sensor Capacity
Ji-Jun Wang, Qiang Zhang, Xing-Xiang Ji, Li-Bin Liu
2020, 38(11): 1221 -1229.   doi: 10.1007/s10118-020-2472-0
[Abstract](341) [FullText HTML](109) [PDF 6261KB](7)
The design and fabrication of conductive hydrogels with high stretchability, compressibility, self-healing properties and good adhesion remains a significant challenge. We have fabricated composite hydrogels by random polymerization of acrylic acid (AA) and dopamine (DA) in the presence of multi-walled carbon nanotubes (MWCNTs). The π-π interaction between DA and MWCNTs makes MWCNTs stably and homogenously dispersed in water. The fabricated PAA-PDA/CNT composite hydrogels possess relatively high mechanical strength (maximum Young’s modulus: 800 kPa) and can be stretched to 1280% strain and compressed to 80% strain. The multiple hydrogen bonding formed between functional groups of PAA-PDA and MWCNTs can effectively dissipate energy and quickly achieve self-healing. The composite hydrogels also show good adhesion and can easily adhere to various inorganic or organic surfaces. In addition, the hydrogel reveals stable strain sensitivity and can be used as skin sensors.
Increased Hydrogen-bonding of Poly(m-phenylene isophthalamide) (PMIA) with Sulfonate Moiety for High-performance Easily Dyeable Fiber
Na Li, Xing-Ke Zhang, Jun-Rong Yu, Yan Wang, Jing Zhu, Zu-Ming Hu
2020, 38(11): 1230 -1238.   doi: 10.1007/s10118-020-2416-8
[Abstract](466) [FullText HTML](231) [PDF 700KB](9)
The demand for high thermal stability and high strength agents is growing steadily as a result of their increasing application in advanced materials. A series of sulfonated poly(m-phenyleneisophthalamide) (SPMIA) copolymers with superior thermal stability and good mechanical properties have been prepared via low temperature polycondensation method. Then the structures of SPMIA copolymers with different content quantities of 2,4-diaminobenzenesulfonic acid (2,4-DABSA) were confirmed by Fourier transform infrared (FTIR). Besides, their superior thermal properties were systematically investigated by differential scanning calorimetry (DSC), thermalgravimetreic analysis (TGA), and dynamic mechanical analysis (DMA). SPMIA fibers were obtained by wet spinning using the resultant SPMIA solutions. In addition, the obtained SPMIA fibers were proved to combine enhanced mechanical properties and unprecedented dyeability. Significantly, the SPMIA fiber with great mechanical property, thermal stability, and dyeability shows great potential in easily dyeing high-performance protective fibers.
Enhancement of β-Phase Crystal Content of Poly(vinylidene fluoride) Nanofiber Web by Graphene and Electrospinning Parameters
Lu Jin, Yan Zheng, Ze-Kun Liu, Jia-Shen Li, Yang-Pei-Qi Yi, Yang-Yang Fan, Lu-Lu Xu, Yi Li
2020, 38(11): 1239 -1247.   doi: 10.1007/s10118-020-2428-4
[Abstract](491) [FullText HTML](206) [PDF 1824KB](20)
Electrospun poly(vinylidene fluoride) (PVDF) nanofiber web has been widely utilized as a functional material in various flexible sensors and generators due to its high piezoelectricity, ease processability, and low cost. Among all the crystalline phases of PVDF, β-phase is a key property for PVDF nanofiber web, because the content of β-phase is directly proportional to piezoelectric performance of PVDF nanofiber web. Herein, the impact of graphene content (GC), tip-to-collector distance (TCD), and rotational speed of collector (RSC), as well as their interactions on the β-phase formation of PVDF nanofiber web is systematically investigated via design of experimental method. The fraction of each crystalline phase of PVDF nanofiber web is calculated by FTIR spectra, and the crystallinity is determined by XRD patterns. The influences of GC, TCD, and RSC on both β-phase fraction and crystallinity of PVDF nanofiber are analyzed using Minitab program. The results show that GC, TCD, and RSC all have significant effect on the β-phase content of PVDF nanofiber web, and GC is the most significant one. In addition, an optimal electrospinning condition (GC = 1 wt%, TCD = 4 cm, and RSC = 2000 r·min–1) to fabricate high β-phase crystallinity of PVDF nanofiber web is drawn, under which the crystallinity can reach 41.7%. The contributions in this study could provide guidance for future research on fabricating high performance PVDF nanofiber web based sensors or generators.
Effect of Olefin-based Compatibilizers on the Formation of Cocontinuous Structure in Immiscible HDPE/iPP Blends
Fei Yang, Li Pan, Hui-Zhen Du, Zhe Ma, Yue-Sheng Li
2020, 38(11): 1248 -1257.   doi: 10.1007/s10118-020-2433-7
[Abstract](595) [FullText HTML](157) [PDF 2886KB](16)
In this work, the formation of cocontinuous structure in immiscible high density polyethylene/isotactic polypropylene (HDPE/iPP) blends was investigated for various olefin-based compatibilizers of distinct molecular architectures, including ternary random copolymer EPDM, olefin block copolymer (OBC), polypropylene-based OBC (PP-OBC), ethylene/α-olefin copolymer (POE), bottlebrush polymer poly(1-dodecene), and comb-like poly(propylene-co-high α-olefin) (PPO). The scanning electron microscopy results show that after adding OBC, PP-OBC, and POE copolymers, the finer droplet-in-matrix morphologies were obtained in 70/30 HDPE/iPP blend. Interestingly, for 70/30 HDPE/iPP blend with just 5 wt% of PPO copolymers, the phase inversion from droplet-in-matrix to cocontinuous morphology can be observed. It was proposed that the development of cocontinuous morphology contained the following steps: (1) interfacial saturation of compatibilizers and droplet deformation, (2) droplet-droplet coalescence, (3) continuity development, and (4) the formation of dual-phase continuity. Among the diverse copolymers studied in this work, PPO copolymer can be easily removed out of the interface during droplet coalescence and stabilize the curvature of minor fiber phase, facilitating the formation of cocontinuous morphology. In contrast, other olefin-based compatibilizers (EPDM, OBC, PP-OBC, and POE) exhibit the distinct steric repulsion effect to prohibit droplet coalescence. Moreover, the cocontinous interval varies with the compatibilizer architectures. Surprisingly, after adding 10 wt% of PPO copolymers, the cocontinuous interval was greatly broadened from HDPE/iPP range of 45/55−60/40 to that of 40/60−70/30.
PEN/BADCy Interlayer Dielectric Films with Tunable Microstructures via an Assist of Temperature for Enhanced Frequency Stability
Xi-Ting Lei, Li-Fen Tong, Ming-Zhen Xu, Yong You, Xiao-Bo Liu
2020, 38(11): 1258 -1266.   doi: 10.1007/s10118-020-2417-7
[Abstract](411) [FullText HTML](176) [PDF 4135KB](11)
Low dielectric interlayer films have become an important element to ensure the development of the microelectronics industry. A kind of flexible interlayer dielectrics, polyarylene ether nitrile/bisphenol A cyanate ester (PEN/BADCy) film, with good thermal stability and low frequency dependence, has been developed by solution casting method. Herein, materials were designed to incorporate bisphenol A cyanate ester as a part of blend, contributing to the frequency stability and structural integrity. The morphological study combined with electron microscopy revealed the uniform and flexible microstructure information with controllable morphology through self-polymerization of cyanate esters with different prepolymerization time and curing temperatures. The dielectric films could present high thermal stability with Tg > 180 °C. Significant improvement in the dielectric properties was achieved for the dielectric constant and loss was much stabler than neat PEN over the frequency range from 100 Hz to 5 MHz. When the prepolymerization time was 3 h and final curing temperature reached 230 °C, the dielectric constant and dielectric loss of the films were 3.36 and 0.013 at 100 kHz, respectively. The dimensional stability (CTE = 53.67 × 10−6 K−1) was confirmed and considered beneficial to use as an interlayer dielectrics.
Sustainable Blends of Poly(propylene carbonate) and Stereocomplex Polylactide with Enhanced Rheological Properties and Heat Resistance
Yi Li, Yan-Cun Yu, Chang-Yu Han, Xian-Hong Wang, De-Xin Huang
2020, 38(11): 1267 -1275.   doi: 10.1007/s10118-020-2408-8
[Abstract](530) [FullText HTML](206) [PDF 727KB](20)
Sustainable blends of poly(propylene carbonate) (PPC) and stereocomplex polylactide (sc-PLA) were prepared by melt blending equimolar poly(L-lactic acid) (PLLA) and poly(D-lactide acid) (PDLA) with PPC to form sc-PLA crystals in situ in the melt blending process. Differential scanning calorimetry analysis revealed that only sc-PLA, no homo-crystallization of PLLA or PDLA, formed in the PPC matrix as the sc-PLA content was more than 10 wt%. Very intriguingly, scanning electronic microscopy observation showed that sc-PLA was evenly dispersed in the PPC phase as spherical particles and the sizes of sc-PLA particles did not obviously increase with increasing sc-PLA content. As a consequence, the rheological properties of PPC were greatly improved by incorporation of sc-PLA. When the sc-PLA content was 20 wt%, a percolation network structure was formed, and the blends showed solid-like behavior. The sc-PLA particles could reinforce the PPC matrix, especially at a temperature above the glass transition temperature of PPC. Moreover, the Vicat softening temperature of PPC/sc-PLA blends could be increased compared with that of neat PPC.
Correction to “Enhanced Crystallization Rate of Poly(L-lactide)/Hydroxyapatite-graft-poly(D-lactide) Composite with Different Processing Temperatures”
Min Wang, Lei-Chu You, Yu-Qi Guo, Ni Jiang, Zhi-Hua Gan, Zhen-Bo Ning
2020, 38(11): 1276 -1276.   doi: 10.1007/s10118-020-2478-7
[Abstract](70) [FullText HTML](48) [PDF 389KB](0)