Browse Articles

Articles in press, not assigned to volumes/issues, but citable by DOI.

Display Method:      

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
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
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
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
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
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
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
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
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.
Highly Stretchable, Compressible, Adhesive, Conductive Self-healing Composite Hydrogels with Sensor Capacity
Ji-Jun Wang, Qiang Zhang, Xing-Xiang Ji, Li-Bin Liu
Corrected proof , doi: 10.1007/s10118-020-2472-0
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.
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
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.
Ultrasmall Nanoparticle ROS Scavengers Based on Polyhedral Oligomeric Silsesquioxanes
Zhan Li, Haotian Li, Jianhua Zhang, Xianhu Liu, Zhipeng Gu, Yiwen Li
Corrected proof , doi: 10.1007/s10118-020-2486-7
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.
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
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
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
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
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
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
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
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
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.
Facile Synthesis of High Molecular Weight Polypeptides via Fast and Moisture Insensitive Polymerization of α-Amino Acid N-Carboxyanhydrides
Yue-Ming Wu, Wei-Wei Zhang, Rui-Yi Zhou, Qi Chen, Chen-Yu Xie, Heng-Xue Xiang, Bin Sun, Mei-Fang Zhu, Run-Hui Liu
Corrected proof , doi: 10.1007/s10118-020-2471-1
Polypeptides have been widely utilized in the fields of biomaterials and biomedicine. Ever since N-carboxyanhydride (NCA) was reported by Hermann Leuchs in 1906, ring-opening polymerization of NCAs has been extensively used to prepare polypeptides. Despite continuous innovations, it is still challenging to synthesize polypeptides in high molecular weight efficiently. To address this challenge, we developed KHMDS/NaHMDS initiated fast NCA polymerization that is also moisture tolerant, open-flask amenable and terminal tunable. This NCA polymerization was able to proceed in most common solvents and meet the solubility requirement of variable NCA monomers and corresponding polypeptides. KHMDS can initiate γ-benzyl-L-glutamate-N-carboxyanhydride (BLG NCA) polymerization in a reaction rate 92 times faster than does hexylamine and 80 times faster than does triethylamine. This NCA polymerization also demonstrated easy and fast synthesis of gram-scale long chain polypeptides in an open flask.
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
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.
Syntheses of Soluble Biopolyimides Using 4-Aminophenylalanine
Kenji Takada, Hiromasa Shinagawa, Yuki Morita, Manjit S. Grewal, Kazuya Taya, Amit Kumar, Tatsuo Kaneko
Corrected proof , doi: 10.1007/s10118-020-2450-6
4-Aminophenylalanine (4APhe), an exotic amino acid which is obtained as a microorganism metabolite of glucose, is polycondensed with various tetracarboxylic dianhydrides as a diamine monomer to obtain poly(amic acid)s. Subsequent thermal imidization of poly(amic acid)s is made at 220 °C with stepwise heating from 100 °C. Some of the obtained polyimides (PIs) exhibited good solubility in organic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and more. The progress of imidization was observed by proton nuclear magnetic resonance and infrared spectroscopy to confirm that the imidization ratio was up to 98%. Carboxylate group of the side-chains of PIs affected their solubilities despite the high imidization ratio, and the solubility was lost for any organic solvents by decarboxylation at 280 °C, confirmed from mass-loss of thermogravimetric analysis. Thus, a new series of PIs were obtained with abilities of solvent-molding in PI state and thermal resistivity enhancement by further heating after molding.
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
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.
A Review of Chitin Solvents and Their Dissolution Mechanisms
Yi Zhong, Jie Cai, Li-Na Zhang
Corrected proof , doi: 10.1007/s10118-020-2459-x
Chitin is an abundant natural nitrogen-containing biopolymer with great application potential in materials, environment, energy, and health. However, the structure characteristics and processing technologies have required intense research in related applications. In particular, there have been great efforts to developing solvents for chitin, and the results so far are quite encouraging. This review summarizes the main solvent systems used for chitin, namely the aqueous solvent systems (mineral acids, inorganic salt aqueous solutions, alkali aqueous solutions) and non-aqueous ones (LiCl-dimethylacetamide solvents, CaCl2·2H2O saturated methanol, ionic liquids, deep eutectic solvents, and protic organic solvents). The solvent properties, dissolution methods, and solution properties are discussed in detail. Special attention is paid to the dissolution mechanism in each system. This review can provide a reference for understanding the dissolution behavior of chitin and finding suitable solvents for it.
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
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
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
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
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
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
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.
The Effect of Oxygen to Salen-Co Complexes for the Copolymerization of PO/CO2
Ran-Long Duan, Yan-Chuan Zhou, Zhi-Qiang Sun, Yue-Zhou Huang, Xuan Pang, Xue-Si Chen
Corrected proof , doi: 10.1007/s10118-020-2451-5
A series of Salen-Co(II) complexes were synthesized to study the effect of O2 on the catalytic performance of Salen-Co complexes for the copolymerization of PO/CO2. The Salen-Co(II) complexes showed low activity on the cyclo-addition of CO2 to PO with the aid of a cocatalyst such as PPNCl. Unexpectedly, with the addition of O2, the activity of Salen-Co(II) complexes was obviously increased and 100% cyclic carbonate was obtained. As the pressure of O2 increased, the activity of the complex also increased. With the existence of O2, the activity of the complexes was influenced by their structures and the pressure of O2, and the complexes with the conjugated structure showed higher activity. The structures of cocatalyst also played a crucial role as for the change of the activity. By altering the electrophilicity of Salen-Co(III), O2 can also be used as cocatalyst for the copolymerization of PO/CO2.
Improvement in Toughness of Poly(ethylene 2,5-furandicarboxylate) by Melt Blending with Bio-based Polyamide11 in the Presence of a Reactive Compatibilizer
Yong Yang, An-Ping Tian, Ya-Jin Fang, Jing-Gang Wang, Jin Zhu
Corrected proof , doi: 10.1007/s10118-020-2449-z
The objective of this study was to improve the toughness of bio-based brittle poly(ethylene 2,5-furandicarboxylate) (PEF) by melt blending with bio-based polyamide11 (PA11) in the presence of a reactive multifunctional epoxy compatibilizer (Joncryl ADR®-4368). The morphological, thermal, rheological, and mechanical properties of PEF/PA11 blends were investigated. Compared with neat PEF, the toughness of PEF/PA11 blend was not improved in the absence of the reactive compatibilizer due to the poor compatibility between the two polymers. When Joncryl was incorporated into PEF/PA11 blends, the interfacial tension between PEF and PA11 was obviously reduced, reflecting in the fine average particle size and narrow distribution of PA11 dispersed phase as observed by scanning electron microscopy (SEM). The complex viscosities of PEF/PA11 blends with Joncryl were much higher than that of PEF/PA11 blend, which could be ascribed to the formation of graft copolymers through the epoxy groups of Joncryl reacting with the end groups of PEF and PA11 molecular chains. Thus, the compatibility and interfacial adhesion between PEF and PA11 were greatly improved in the presence of Joncryl. The compatibilized PEF/PA11 blend with 1.5 phr Joncryl exhibited significantly improved elongation at break and unnotch impact strength with values of 90.1% and 30.3 kJ/m2, respectively, compared with those of 3.6% and 3.8 kJ/m2 for neat PEF, respectively. This work provides an effective approach to improve the toughness of PEF which may expand its widespread application in packaging.
Stereocomplexed Poly(lactide) Composites toward Engineering Plastics with Superior Toughness, Heat Resistance and Anti-hydrolysis
Bao-Gou Wu, Wei-Jun Yang, De-Yu Niu, Wei-Fu Dong, Ming-Qing Chen, Tian-Xi Liu, Ming-Liang Du, Pi-Ming Ma
Corrected proof , doi: 10.1007/s10118-020-2443-5
Poly(lactide), PLA, suffers from brittleness and low heat deflection temperature (HDT), which limits its application as an engineering plastic. In this work, poly(L-lactide)/poly(D-lactide)/ethylene-vinyl acetate-glycidyl methacrylate random copolymer (PLLA/PDLA/EVM-GMA = 1/1/x) composites were prepared by melt blending, and the in situ formed EVM-g-PLA copolymers improved the compatibility between PLA and EVM-GMA. Subsequently, the blends were subjected to a two-step annealing process during compression molding, i.e. first annealing at 120 °C to rapidly form a certain amount of stereocomplex (sc) crystallites as nucleation sites, and then annealing at 200 °C to guide the formation of new sc crystallites. Both differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) measurements confirmed the formation of highly stereocomplexed PLA products. Mechanical results showed that the PLLA/PDLA blend with 20 wt% of EVM-GMA had a notched impact strength up to 65 kJ/m2 and an elongation at break of 48%, while maintaining a tensile strength of 40 MPa. Meanwhile, dynamic mechanical analysis (DMA) and heat deflection tests showed that the PLA composite had an HDT up to 142 °C which is 90 °C higher than that of normal PLA products. Scanning electron microscopy (SEM) confirmed the fine dispersion of EVM-GMA particles, which facilitated to understand the toughening mechanism. Furthermore, the highly stereocomplexed PLA composites simultaneously exhibited excellent chemical and hydrolysis resistance. Therefore, these fascinating properties may extend the application range of sc-PLA material as an engineering bioplastic.
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
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
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
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
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
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
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
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.
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
Corrected proof , doi: 10.1007/s10118-020-2431-9
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.
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
Corrected proof , doi: 10.1007/s10118-020-2433-7
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.
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
Corrected proof , doi: 10.1007/s10118-020-2428-4
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.
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
Corrected proof , doi: 10.1007/s10118-020-2425-7
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 Frasier-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.
Synthesis and Properties Investigation of Thiophene-aromatic Polyesters: Potential Alternatives for the 2,5-Furandicarboxylic Acid-based Ones
Jing-Gang Wang, Xiao-Qin Zhang, Ang Shen, Jin Zhu, Ping-An Song, Hao Wang, Xiao-Qing Liu
Corrected proof , doi: 10.1007/s10118-020-2438-2
In order to explore new substitutes for 2,5-furandicarboxylic acid (FDCA) or poly(ethylene 2,5-furandicarboxylate) (PEF) and try to develop more ideal bio-based polyesters, several thiophene-aromatic polyesters (PETH, PPTH, PBTH, and PHTH) were synthesized from dimethyl thiophene-2,5-dicarboxylate (DMTD) and different diols, including ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol. The chemical structures of obtained polyesters were confirmed by nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR). Determined by GPC measurement, their average molecular weight (Mw) varied from 5.22 × 104 g/mol to 7.94 × 104 g/mol with the molar-mass dispersity of 1.50−2.00. Based on the DSC and TGA results, the synthesized polyesters PETH, PPTH, and PBTH displayed comparable or even better thermal properties when compared with their FDCA-based analogues. From PETH to PHTH, their Tg varied from 64.6 °C to −1 °C while T5% ranged from 409 °C to 380 °C in nitrogen atmosphere. PETH showed elongation at break as high as 378%, tensile strength of 67 MPa, and tensile modulus of 1800 MPa. Meanwhile, the CO2 and O2 barrier of PETH was 12.0 and 6.6 folds higher than those of PET, respectively, and similar to those of PEF. Considering the overall properties, the synthesized thiophene-aromatic polyesters, especially PETH, showed great potential to be used as an excellent bio-based packaging material in the future.
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
Corrected proof , doi: 10.1007/s10118-020-2446-2
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.
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
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.
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
Corrected proof , doi: 10.1007/s10118-020-2441-7
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.
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
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.
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
Corrected proof , doi: 10.1007/s10118-020-2430-x
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 .
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
Corrected proof , doi: 10.1007/s10118-020-2426-6
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%.
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
Corrected proof , doi: 10.1007/s10118-020-2421-y
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.
Mechanical Properties, Crystallization and Biodegradation Behavior of the Polylactide/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/Poly(butylene adipate-co-terephthalate) Blown Films
Xiang-Yu Wang, Hong-Wei Pan, Shi-Ling Jia, Zeng-Wen Cao, Li-Jing Han, Hui-Liang Zhang, Li-Song Dong
Corrected proof , doi: 10.1007/s10118-020-2418-6
Polylactide (PLA), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), and poly(butylene adipate-co-terephthalate) (PBAT) ternary blends were prepared by extrusion blending. The biodegradable PLA/P(3HB-co-4HB)/PBAT films were successfully obtained by using blown films technique. Excellent stiffness-toughness balance was achieved for 55/10/35 PLA/P(3HB-co-4HB)/PBAT film. The tensile strength reached 33.0 MPa (MD) and 23.5 MPa (TD), the elongation at break exceeded 130 %, and tear strength exceeded 110 kN/m. The Young′s modulus as low as about 1800 MPa also met packaging applications. SEM observations revealed rough and long ligaments, indicating that the tear specimens were broken yieldingly. The addition of PBAT elastomers was the main reason for the improved toughness of the film. From DMA and SEM analysis, it was demonstrated that PLA, P(3HB-co-4HB), and PBAT were partially compatible. With increasing P(3HB-co-4HB) content, the melt and cold crystallization of PLA was promoted. The enzymatic degradation experiments indicated that the films had good biodegradability. These findings gave important implications for designing and manufacturing biodegradation package of high biological carbon content.
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
Corrected proof , doi: 10.1007/s10118-020-2417-7
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.
Antistatic Structural Color and Photoluminescent Membranes from Co-assembling Cellulose Nanocrystals and Carbon Nanomaterials for Anti-counterfeiting
Si-Yuan Liu, Yan-Bin Gong, Shan Ma, Yu-Huan Wang, Lin Gan, Jin Huang
Corrected proof , doi: 10.1007/s10118-020-2414-x
Static charges on optical anti-counterfeiting membranes may lead to materials structural changes, dust stain aggravation, and misreading of optical information. Incorporating conductive particles is a common way to transfer accumulative charges, but the key issue is how to achieve high dispersion and effective distribution of particles. According to the strategy of assembly-induced structural colors, cellulose nanocrystals (CNCs) were employed as a solid emulsifier to stabilize hydrophobic carbon nanoparticles (CNPs) in aqueous media; subsequently, by solvent-evaporation-modulated co-assembly under a condition of 30 °C and 20 RH%, the binary suspensions containing 2 wt% CNC and CNPs with the equivalent concentration relative to CNC ranged from 1:40 to 1:10 were used to prepare antistatic composite membranes. Surface chemistry regulation of CNCs was applied to optimize the dispersibility of CNPs and the orientation of assembled CNC arrays, and the hydrophilic CNCs were more favorable for dispersion and assembly of binary suspension systems. Meanwhile, one-dimension carbon nanotube (CNT) and zero-dimension carbon black (CB) were found to show better dispersibility than two-dimension graphene, which was verified by a semi-quantitative theoretical study. Moreover, the stable binary systems of CNT/CNC and CB/CNC were chosen for co-assembly as membranes, and the uniaxial orientation could be optimized as the full-width of 9.8° at half-maximum deviation angle while the surface resistivity could also drop down to 3.42 × 102 Ω·cm·cm−1. The structural color character of such paper-homology and antistatic-integrated membranes contributes to optical information hiding-and-reading, and shows great potential as optical mark recognition materials for electrostatic discharge protective packaging and anti-counterfeiting applications.
Preparation of Degradable Polymenthide and Its Elastomers from Biobased Menthide via Organocatalyzed Ring-opening Polymerization and UV Curing
Na Zhao, Xin-Xin Cao, Jin-Feng Shi, Zhi-Bo Li
Corrected proof , doi: 10.1007/s10118-020-2415-9
Development of degradable polyester elastomers plays an important role in the applications of soft mateirals. Noncrystalline polymenthides (PMs) from menthol derived lactone monomers are excellent soft segments for preparing degradable polyester elastomers. By using cyclic trimeric phosphazene base (CTPB) as an organocatalyst, we successfully synthesized PMs with different molecular weights (8.2 kDa to 100.7 kDa) in high yields via ring-opening polymerization (ROP) of menthide. When a CTPB/urea binary catalytic system was adopted, the polymerizations proceeded in a more controlled manner. Using glycerol as initiator, star shaped PMs with well-defined structure were synthesized and subsequently end-capped by acrylate. UV irradiation of the terminal acrylate groups in the star-shaped PMs resulted in formation of chemically cross-linked polyester elastomers without heat or other stimuli. The obtained polyester elastomers exhibit matched modulus (3.8−5.5 MPa), tensile strength (0.56−0.68 MPa), and strain at break (280%−320%) with soft body tissues, displaying great potential in biomedical applications.
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
Corrected proof , doi: 10.1007/s10118-020-2416-8
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.
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
Corrected proof , doi: 10.1007/s10118-020-2408-8
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.
Preparation of Hydrophilic UHMWPE Hollow Fiber Membranes by Chemically Bounding Silica Nanoparticles
Lianlian Fan, Jiayou Quan, Hao Zhang, Junrong Yu, Zuming Hu, Yan Wang
Accepted Manuscript , doi: 10.1007/s10118-021-2507-1
In this article, 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 ATR-FTIR, XPS, 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 VTMS concentration was 13%, the pH value of the hydrolyzate was 4 and the hydrolysis reaction time was 6 hours. 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.
Preparation and Characterization of Attractive Poly(Amino Acid) Hydrogels Based on 2-Ureido-4[1H]-Pyrimidinone
Zhen Shi, Qi Wang, Guifei Li, Yufeng Shou, Hongjie Zong, Shifeng Yan, Kunxi Zhang, and Jingbo Yin
Accepted Manuscript , doi: 10.1007/s10118-021-2498-y
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 hardly be excreted from the body, considerably limiting their bio-application. Here, using poly(l-glutamic acid) (PLGA) as biodegradable matrix, through 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 have 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 hours, 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.
Super strong and tough elastomers enabled by sacrificial segregated network
Yong Zhu, Laiyun Wei, Xuan Fu, Junqi Zhang, Lingmin Kong, Guangsu Huang, and Jinrong Wu
Accepted Manuscript , doi: 10.1007/s10118-020-2484-9
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.
An ultrasensitive, durable and stretchable strain sensor with crack-wrinkle structure for human motion monitoring
Zeyu Li, Wei Zhai, Yunfei Yu, Guojie Li, Pengfei Zhan, Jianwei Xu, Guoqiang Zheng, Kun Dai, Chuntai Liu, Changyu Shen
Accepted Manuscript , doi: 10.1007/s10118-021-2500-8
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 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 fast respond time of 90 ms. For the sensing service behaviors, the CWS sensor exhibits an ultrahigh durability (high stability> 20000 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.
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 and Yu-zhong Wang
Accepted Manuscript , doi: 10.1007/s10118-020-2492-9
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%).
Thienylmethylene oxindole based conjugated polymers via direct arylation polymerization and their electrochromic properties
Wei Yang, Haoguo Yue, Dong Zhao, Hui Yan, Kangli Cao, Jinsheng Zhao, Qing Zhang
Accepted Manuscript , doi: 10.1007/s10118-021-2503-5
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 to +1.5 V, and showed high coloration efficiencies (436~438 cm2 C-1) in near-infrared regions with fast switching speeds around 1~2 seconds under ambient conditions.
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, and Fu-sheng Liu
Accepted Manuscript , doi: 10.1007/s10118-021-2504-4
Photo-responsive mechanical actuator is a classic of stimuli-responsive materials transferred light to mechanical energy through macroscopic transformation. To fabricate photo-responsive mechanical actuator, soft polymeric materials crosslinked with functional bridging structures is 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 microcosmic photo-isomerization of 4,4'-dihydroxyazobenzene. Meanwhile, the photo-responsive mechanical actuator can also lift weight which is up to 200 times heavier than 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 design and synthesize photo-responsive mechanical actuator suitable for large-scale manufacturing industrialization in future.
Benzotriazole based 2D-conjugated Polymer Donors for High Performance Polymer Solar Cells
Zhi-Guo Zhang, Yang Bai, Yongfang Li
Accepted Manuscript , doi: 10.1007/s10118-020-2496-5
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.
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, and Dong Liu
Accepted Manuscript , doi: 10.1007/s10118-020-2485-8
The correlation between aggregates and bound rubber structures in silicone rubbers (S(phr)) with various silica fraction (ΦSi) has been investigated by contrast matching small-angle neutron scattering (SANS), swelling kinetics, and low-field Nuclear magnetic resonance (NMR). Mixed solvent 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 phr and 30 phr. Below ΦSic, the isolated aggregates are dominant, while surpass 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. 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 should’ve existent bicontinuous network in dry samples with less ΦSi are kind of impacted by swelling. With the obtained bound rubber models, the reinforcing mechanism of filled silicone rubber is elucidated.
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 and Li-Jia An
Accepted Manuscript , doi: 10.1007/s10118-020-2487-6
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 W_i=12.6 to W_i=12640. At weak shear flow Wi = 12.6, the shear stress proportionally increases with shear strain in 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 with time, 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 those at Wi = 12.6, namely, disappeared strain hardening and dramatic increment of stress at large strains, which is caused by the serious 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 with the performance of shear and the stress-strain curve has the similar behaviors with those of classical polymeric liquids.
Cellulose Acetate Thermoplastics with High Modulus, Dimensional Stability and Anti-Migration Properties by Using CA-g-PLA as Macromolecular Plasticizer
Rumeng Xu, Tiantian Yang, Elvira Vidović, Ruonan Jia, Jinming Zhang, Qinyong Mi, Jun Zhang
Accepted Manuscript , doi: 10.1007/s10118-020-2470-2
Cellulose diacetate (CDA) can be melt processed to produce numerous and widely-used plastic products. However, due to the high glass transition temperature (Tg) of CDA, the addition of up to 30 w% of micromolecular plasticizers is indispensable, which significantly reduces the dimensional stability and raises safety concerns from the migration of plasticizers. In this work, a series of CDA-graft-poly(lactic acid) (CDA-g-PLA) copolymers were synthesized by ring-opening polymerization of lactide onto the hydroxyl groups of CDA. The resultant CDA-g-PLA copolymers possess adjustable degrees of substitution (DSPLA) and side chain length (DPPLA) by controlling the reaction time and feed ratio. The Tgs and thermal flow temperatures (Tfs) of CDA-g-PLA strongly depend on DPPLA, such as the Tgs decrease linearly with the increase of DPPLA. The CDA-g-PLA copolymers with the DPPLA of 3-9 can be directly processed to transparent plastics by melt processing without any external plasticizers, because of their low Tfs of 170-215 ℃. More impressively, the CDA-g-PLA can act as the macromolecular plasticizer. The obtained CDA/CDA-g-PLA has higher storage modulus, flexural modulus and Young's modulus than the commercial CDA plasticized with triethyl citrate. In addition, the CDA/CDA-g-PLA exhibits high dimensional stability and anti-migration property. During a long-term treatment at 80 C and 60 % humidity, the CDA/CDA-g-PLA can retain the initial shape. Therefore, this work not only proposes a facile method to achieve a direct thermoplastic processing of CDA, but also provides a macromolecular plasticizer for CDA to make lightweight, stable and safer biobased thermoplastics.
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, and Dong-Mei Cui
Accepted Manuscript , doi: 10.1007/s10118-021-2505-3
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 ºC. 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.
Thermoresponsive Nanogels from Dendronized Copolymers for Complexation, Protection and Release of Nucleic Acids
Yi Yao, Jianhui Wu, Shijie Cao, Biyi Xu, Jiatao Yan, Di Wu, Wen Li, and Afang Zhang
Accepted Manuscript , doi: 10.1007/s10118-020-2452-4
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 hour 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 novel class of scaffolds as promising materials for biomedical applications.
Effect of the nanoparticle functionalization on the cavitation and crazing process in the polymer nanocomposites
Yanlong Luo, Tiantian Li, Bin Li, Xianling Chen, Zhenyang Luo, Yangyang Gao, Liqun Zhang
Accepted Manuscript , doi: 10.1007/s10118-020-2488-5
The nanoparticle (NP) functionalization is an effective method to enhance 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 which hope 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 while it shows a continuous increase with increasing the interaction between polymer and modified beads. The bond orientation degree is first characterized which is referred to the elongation. Meanwhile, the stress by polymer chains is gradually reduced with increasing the or the while it by NPs is enhanced. Furthermore, the percentage of stress by polymer chains first increases and then decreases with increasing the strain while it 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 the or . As a result, the number of voids first increases and then decreases with increasing the while it continuously declines with the . In summary, our work provides a clear understanding how the NP functionalization influences the cavitation and crazing process during the fracture process.
Facile Mechanochemical Preparation of Polyamide-derivatives via Solid-state Benzoxazine-isocyanide Chemistry
Xu Sun, Wei Shi, Xin-yu Zhou, and Sheng Ding
Accepted Manuscript , doi: 10.1007/s10118-021-2510-6
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 dosage 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, verifying the adaptability of ssBIC thus. Structural characterization indicates that amide, phenolic hydroxyl and tertiary amine substructures, which 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.
Temperature-Dependent Crystallization and Phase Transition of P(L-lactic acid)/CO2 Complex Crystals
Ying Zheng, Cailiang Zhang, Yongzhong Bao, Guorong Shan, Pengju Pan
Accepted Manuscript , doi: 10.1007/s10118-021-2502-6
Semicrystalline polymers can crystallize in the unique crystalline polymorph and show different phase behavior 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  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  crystals. The PLLA/CO2 complex crystals were metastable and transformed into the thermally stable  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  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, Wenhong Yang, Yu Wang, Ping Zhu, Jingpu Li, Xia Dong, Dujin Wang
Accepted Manuscript , doi: 10.1007/s10118-020-2494-7
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 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. Experiential and molecular dynamics simulation for pure hard segments that are as 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.
Combined Molecular Dynamics Simulation and Rouse Model Analysis of Static and Dynamic Properties of unentangled Polymer Melts with Different Chain Architectures
Pu Yao, Lukun Feng, Hongxia Guo
Accepted Manuscript , doi: 10.1007/s10118-020-2489-4
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 internal distance (MSID) can be well described by Wittmer’ theory for linear chains and the resulted 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 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 chain length 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.
Effect of Interfacial Adsorption on the Stability of Thin Polymer Films in a Solvent-Induced Process
Lin Xu, Tongfei Shi, Lijia An, Yuyuan Lu, Lina Wang
Accepted Manuscript , doi: 10.1007/s10118-020-2493-8
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 times, 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 times, 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.
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, and Run-Hui Liu
Accepted Manuscript , doi: 10.1007/s10118-021-2506-2
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 tack 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.
A Potential Alternative to Polystyrene: Ring-opening Terpolymerization of Different Epoxides with Phthalic Anhydride Using Metal-free Dual Catalysts
Limiao Lin, Yonghang Xu, Man Shen, Jiaxin Liang, Shuanjin Wang, Min Xiao, Yuezhong Meng
Accepted Manuscript , doi: 10.1007/s10118-020-2495-6
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 ratio 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.
Styrene-Containing Phosphine-Sulfonate Ligands for Nickel- and Palladium-Catalyzed Ethylene Polymerization
Shabnam Behzadi, Chen Zou, Bangpei Yang, Chen Tan and Changle Chen
Accepted Manuscript , doi: 10.1007/s10118-021-2509-z
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 the 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 oC) versus the counterparts bearing 3-/4-vinyl groups as well as previously reported phosphine-sulfonate Ni complexes bearing bulky biaryl substituents.
Flexible electrochromic poly(thiophene-furan) film via electrodeposition with high stability
Wenqian Yao, Peipei Liu, Weiqiang Zhou, Xuemin Duan, Jingkun Xu, Jiaji Yang, Shouli Ming, Meng Li, and Fengxing Jiang
Accepted Manuscript , doi: 10.1007/s10118-021-2501-7
Flexible electrochromic (EC) materials have an urgent demand in the current electronic equipment market due to its 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 paper, we have successfully synthesized a novel thiophene-furan (TFu) monomer via Still coupling reaction, and facile 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 analysis 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 T (32.1 %), faster response time (1.38 s), excellent 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.

Display Method:          |     

2020, 38(9): 0 -0.  
Transformation of Commodity Poly(hydroxyether of bisphenol A) into Vitrimers via Post Crosslinking with Hindered Urea Bonds
Hao Ding, Bingjie Zhao, Honggang Mei, Lei Li, Sixun Zheng
2020, 38(9): 915 -920.   doi: 10.1007/s10118-020-2457-z
In this contribution, we reported the preparation of vitrimers by using commodity thermoplastics via post crosslinking with hindered urea bonds (HUBs). First, three hindered urea diisocyanates (HUDIs) were synthesized via the reactions of N,N′-di-tert-butylethylenediamine, N,N′-diethylethylenediamine, and piperazine with isophorone diisocyanate (IPDI). Thereafter, these HUDIs were used as the crosslinking agents to crosslink poly(hydroxyether of bisphenol A) (PH), a commodity thermoplastics. Fourier transform infrared (FTIR) spectroscopy and dynamic mechanical thermal analyses (DMTA) indicated that the PH thermosets were successfully obtained. It was found that the thermosets displayed the behavior of vitrimers. The PH thermosets can be reprocessed at elevated temperature without using catalyst and the mechanical strengths of vitrimers were recovered as high as 95%. The reprocessing properties are attributable to dynamic exchange reaction of hindered urea bonds, contingent on types of hindered urea bonds.
Polyphosphoester-modified Cellulose Nanocrystals for Stabilizing Pickering Emulsion Polymerization of Styrene
Kun-Ming Che, Ming-Zu Zhang, Jin-Lin He, Pei-Hong Ni
2020, 38(9): 921 -931.   doi: 10.1007/s10118-020-2404-z
The structure and properties of functional nanoparticles are important for stabilizing Pickering emulsion polymerization. Recently, cellulose nanocrystals (CNCs) are increasingly favored as a bio-based stabilizer for Pickering emulsions. In this study, we reported a novel functionalized polyphosphoester-grafted CNCs for the stabilization of oil-in-water Pickering emulsions and the emulsion polymerization of styrene. First, polyphosphoester containing an amino group at one end of the chain, abbreviated as PBYP-NH2, was prepared by ring-opening polymerization (ROP) and hydrolysis reaction, wherein PBYP represents poly[2-(but-3-yn-1-yloxy)-2-oxo-1,3,2-dioxaphospholane]. Subsequently, CNC-COOH was obtained via 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation of CNCs. The functionalized nanocrystals CNC-PBYP-COOH with carboxyl groups and polyphosphoester on the surface were obtained by the amidation reaction of PBYP-NH2 with CNC-COOH. Finally, we used CNC-PBYP-COOH as sole particle emulsifiers to stabilize styrene-in-water Pickering emulsions and studied its effects on the emulsions in details by using dynamic light scattering (DLS). The results indicated that the properties of these emulsions depended on the concentration of hydrophobically modified CNCs, volume ratios of oil to water, and pH values. The modified CNCs had higher ability to stabilize the styrene-in-water emulsions relative to the unmodified CNCs, and a stable oil-in-water (o/w) Pickering emulsion with diameter of hundreds of nanometers could be obtained. The resulting emulsions could be polymerized to yield nanosized latexes. The polyphosphoester-modified CNCs as green particle emulsifiers can efficiently stabilize nanoemulsions and latexes, which would promote the development of novel environmentally friendly materials.
Investigation on Self-healing Property of Epoxy Resins Based on Disulfide Dynamic Links
Zi-Jian Li, Jiang Zhong, Mao-Chen Liu, Jin-Chuang Rong, Kun Yang, Ji-Yong Zhou, Liang Shen, Fei Gao, Hai-Feng He
2020, 38(9): 932 -940.   doi: 10.1007/s10118-020-2406-x
Self-healing polymers based on dynamic crosslinkers have drawn rapidly increasing interest over the last decade. Here, a self-healable epoxy network with exchangeable disulfide bonds was synthesized by polymerizing two epoxies with an aromatic amine containing a disulfide bond. The bisphenol A diglycidyl ether (DGEBA) and poly(ethylene glycol) diglycidyl ether (DER736) were used as rigid and soft components, respectively. The crosslinking densities of studied polymers decreased with the increasing amount of DER736, resulting in the lower glassy temperature and weaker mechanical strength. The dynamic covalent network character of disulfide bond and its low active energy were also investigated through stress relaxation experiments at various temperatures. The self-healing performance of healable epoxy resins with varied flexibility was measured by tensile tests. The tensile strength of a full-cut sample was restored to 84% (13 MPa) of the initial values (16 MPa) at moderate temperature. Its healed fracture strain was up to 505%. Moreover, the effect of healing time and temperature on the self-healing properties was also studied. A model was proposed to investigate the self-repairing efficiency evolution with healing time, suggesting that hydrogen bonds mainly contributed to the initial sticking or interfacial adhesion while disulfide links and chain interdiffusion assisted time dependent reformation of networks to restore the original mechanical strength.
Quinolinyl Imidazolidin-2-imine Nickel Catalyzed Efficient Copolymerization of Norbornene with para-Chlorostyrene
Yan-Qing Li, Jian Zhou, Ru Xiao, Zheng-Guo Cai
2020, 38(9): 941 -949.   doi: 10.1007/s10118-020-2400-3
A series of novel quinolinyl imidazolidin-2-imine nickel complexes with different substituents on the imidazolidin-2-imine ligand were synthesized and characterized. The complexes in the presence of methylaluminoxane (MAO) as a cocatalyst catalyzed the copolymerization of norbornene (N) and styrene (S) or para-chlorostyrene (CS) with high activity (up to 1070 kg·mol−1·h−1). The installation of sterically bulky substituents on the imidazolidine-2-imine ligand was effective for the increase of the molecular weight and the comonomer content, affording high molecular weight copolymers with tunable CS content (0.57 mol%−11.7 mol%), in which the existence of Cl group can provide reaction site for the further functionalization of copolymers as well as the synthesis of graft or cross-linked polymers. The linear relationship between the comonomer content and the glass transition temperature of the copolymers and the monomer reactivity ratios in the copolymerization indicated the formation of the expected functionalized cyclic olefin copolymers (COC).
Mechanism-inspired Design of Heterodinuclear Catalysts for Copolymerization of Epoxide and Lactone
Wei-Min Ren, Rui-Jing Wang, Bai-Hao Ren, Ge-Ge Gu, Tian-Jun Yue
2020, 38(9): 950 -957.   doi: 10.1007/s10118-020-2413-y
Polyesters, as a class of high-performance and versatile polymer materials, often suffer from some drawbacks, such as hydrophobicity and brittleness due to their single structure nature. Thus, modifications have attracted much attention for enhancing their desirable properties, of which one efficient way is incorporating the aliphatic polyether segment into the main chain of the polyester. However, this approach is of much challenge because the obtained polyesters are problematic in either low alternating degree or low molecular weight. Herein, we describe an efficient strategy to incorporate polyether fragment into polyester by developing a novel Co-Al based heterodinuclear complex for mediating the copolymerization of propylene oxide (PO) with ε-caprolactone (CL). The tracking experiments reveal that PO and CL convert into the polymer chain throughout the polymerization process. Especially, the linear increase in the molecular weight with conversion of CL indicates the controllable nature of the copolymerization. The competition polymerization, offering the monomer reactivity ratios of rCL = 0.96 and rPO = 1.04, suggests that the tendency of self-propagation or incorporation of monomers is nearly identical. Interestingly, the obtained polymers with different ether contents exhibit tunable thermal properties with enhanced decomposition temperature for the polymer with higher ether content. The newly developed heterodinuclear complex for new polymerization provides an idea to synthesize new functional polymeric materials.
Construction of Ionic Porous Organic Polymers (iPOPs) via Pyrylium Mediated Transformation
Shi-Yue Zhang, Wei-Tao Gong, Wei-Dong Qu, Xiao-Rong Deng, Kai-Xun Dong, Shu-Guang Zhang, Gui-Ling Ning
2020, 38(9): 958 -964.   doi: 10.1007/s10118-020-2436-4
Two new ionic porous organic polymers (iPOPs) with different counter anions were successfully fabricated via well-known pyrylium mediated transformation into pyridinium. 13C solid-state NMR, XPS, and FTIR were analyzed and confirmed the formation of pyridinium in the network. Containing charged and aromatic networks, both iPOPs exhibit a high affinity towards toxic hexavalent chromium Cr(VI) ions. What is more, it has been demonstrated that both CO2 adsorption and Cr(VI) removal properties can be tuned by simply varying counter anions.
Nanofiltration Membranes via Layer-by-layer Assembly and Cross-linking of Polyethyleneimine/Sodium Lignosulfonate for Heavy Metal Removal
Meng-Yun Xie, Jiang Wang, Qing-Yun Wu
2020, 38(9): 965 -972.   doi: 10.1007/s10118-020-2422-x
Layer-by-layer (LbL) assembly technology is a facile method for constructing thin film composite membrane. Herein, a novel nanofiltration (NF) membrane was prepared by LbL assembly of polyethyleneimine (PEI) and sodium lignosulfonate (LS) followed by cross-linking. The surface composition, morphology, and property of PEI/LS bilayer were detailedly investigated by FTIR/ATR, XPS, SEM, AFM, and water contact angle test. The PEI/LS bilayer full of amino and hydroxyl groups presents increased roughness and improved hydrophilicity. Moreover, the NF performance of PEI/LS LbL assembly membranes can be modulated by bilayer number, polyelectrolyte concentration, and salt content. The water flux reduced while the salt rejection greatly improved as increasing the bilayer numbers, PEI concentration, or NaCl content. More than 95% MgSO4 and MgCl2, as well as 80% NaCl can be rejected by a NF membrane prepared by 6 PEI/LS bilayers, 1 wt% PEI, 0.5 wt% LS, and 1 mol/L NaCl. Furthermore, this NF membrane can be used to remove more than 95% heavy metal ions (Cd2+, Zn2+, Mn2+, Cr2+, Cu2+, and Ni2+). This work proposed a promising NF membrane by using PEI/LS as low cost polyelectrolytes and facile LbL assembly method, which should receive much attention in water purification.
Preparation of Titanium-silphenylene-siloxane Hybrid Polymers with High Refractive Index, Transmittance, and Thermal Stability
Dong Zhao, Shu-Xi Shan, Meng Zhang, Xiao-A Zhang, Sheng-Ling Jiang, Ya-Fei Lyu
2020, 38(9): 973 -982.   doi: 10.1007/s10118-020-2398-6
Vinyl-containing titanium-silphenylene-siloxane oligomers ( O1 , O2 , O3 , and O4 ) with different molar ratios of titanium to silicon were successfully synthesized in high yields by nonhydrolytic sol-gel reaction, and the obtained four oligomers were further crosslinked with methylphenyl hydro-silicone oil ( 4 ) to form corresponding polymers ( P1 , P2 , P3 , and P4 ) by hydrosilylation reaction. Their structures were characterized with spectroscopic characterization techniques including FTIR, 1H-NMR, and Raman spectroscopy. The effect of titanium element on crosslinking behavior, thermal resistance, refractive index, transparency, thermal aging stability, glass transition temperature, and surface properties of the polymers were studied. Compared with titanium-free polymer P1 , the thermal resistance, refractive index, and thermal aging stability of titanium-silphenylene-siloxane polymers ( P2 , P3 , and P4 ) were significantly improved. The titanium-silphenylene-siloxane polymers achieved a high refractive index (n = 1.580−1.584) and thermostability (T5d > 500 °C). In thermal aging, the polymers exhibited superior performances with high optical transparency (~90% at 450 nm) and exhibited high thermal stability (~84% at 450 nm after thermal aging at 150 °C for 120 h). These data indicate that the polymers have potential application in optical materials such as LED encapsulants.
Design and Properties of Fluoroelastomer Composites via Incorporation of MWCNTs with Varied Modification
Guang-Yao Yang, Li-Fen Tong, Xiao-Bo Liu
2020, 38(9): 983 -992.   doi: 10.1007/s10118-020-2405-y
Multi-walled carbon nanotubes (MWCNTs) modified with silane coupling agent A-1120 (MWCNTs-A1120) were prepared. Compared with the raw MWCNTs, acidified MWCNTs (MWCNTs-COOH), and MWCNTs grafted with EDA (MWCNTs-NH2), MWCNTs-A1120 have the best dispersion in fluoroelastomer at the same doping ratio. Therefore, fluoroelastomer/MWCNTs-A1120 composite has the best mechanical properties with tensile strength of 13.92 MPa and elongation at break of 111.78%. Then, the effects of doping amount of MWCNTs-A1120 on the electrical properties of the composites were investigated. The dielectric constant of the composite increases with the increase of MWCNTs-A1120, and the dielectric loss does not change much at the low doping amount such as 0.5 wt%. When the doping amount of MWCNTs-A1120 is 5 wt%, the dielectric constant and the dielectric loss value are greatly increased, and the volume resistivity is greatly decreased, which proves that the conductive network is formed in the composite, so the filling amount of 5 wt% is the percolation threshold. The tensile deformation of the sample also affects the electrical properties of the composites. As the tensile deformation increases, the dielectric constant and dielectric loss of the composite decrease. For the composite with 5 wt% MWCNTs-A1120, excessive tensile deformation will destroy the conductive network structure of the composite, so the composite will change from conductive material to dielectric material. Therefore, such composite is a good candidate for flexible conductive material or flexible dielectric material used in harsh environments such as high temperatures and various aggressive solvents.
Time and Temperature Dependence of the Structural Evolution for Polyamide 1012
Xin-Ran Liu, Yu Wang, Li-Yuan Liu, Xia Dong, Du-Jin Wang
2020, 38(9): 993 -998.   doi: 10.1007/s10118-020-2434-6
The rheological property evolution of polyamide 1012 (PA1012) in the isothermal process in molten state has been investigated. The results show that the viscosity increases and crosslinking reaction occurs simultaneously together with the increase of temperature, thus causing the variation of storage modulus (G′) and loss modulus (G″) in the repeated frequency sweeps with residual time. This research has pointed out that the superposition is valid for monitoring the complex behavior composed of the viscosity increasing and crosslink occurring process by tracing the variation behavior of the crossover points of G′ and G″ with time, revealing the same time-temperature dependence of the two reactions in the isothermal process. A normalized master curve has been proposed to describe the melt behavior at a given temperature.
Supergiant Barocaloric Effects in Acetoxy Silicone Rubber over a Wide Temperature Range: Great Potential for Solid-state Cooling
William Imamura, Érik Oda Usuda, Lucas Soares Paixão, Nicolau Molina Bom, Angelo Marcio Gomes, Alexandre Magnus Gomes Carvalho
2020, 38(9): 999 -1005.   doi: 10.1007/s10118-020-2423-9
Solid-state cooling based on caloric effects is considered a viable alternative to replace the conventional vapor-compression refrigeration systems. Regarding barocaloric materials, recent results show that elastomers are promising candidates for cooling applications around room-temperature. In the present paper, we report supergiant barocaloric effects observed in acetoxy silicone rubber—a very popular, low-cost and environmentally friendly elastomer. Huge values of adiabatic temperature change and reversible isothermal entropy change were obtained upon moderate applied pressures and relatively low strains. These huge barocaloric changes are associated both to the polymer chain rearrangements induced by confined compression and to the first-order structural transition. The results are comparable to the best barocaloric materials reported so far, opening encouraging prospects for the application of elastomers in near future solid-state cooling devices.
Revisiting Silica Networks by Small-angle Neutron Scattering and Synchrotron Radiation X-ray Imaging Techniques
Xin-Wei Kang, Dong Liu, Ping Zhang, Ming Kang, Feng Chen, Qing-Xi Yuan, Xiu-Li Zhao, Ying-Ze Song, Li-Xian Song
2020, 38(9): 1006 -1014.   doi: 10.1007/s10118-020-2402-1
The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica. Nevertheless, the filler network structure and corresponding reinforcement mechanism are still under debate and need to be further probed with the aid of applicative advanced analysis techniques. Herein, small-angle neutron scattering (SANS) and synchrotron radiation X-ray nano-computed tomography (Nano-CT) techniques are employed to explore the evolution of filler networks of fumed, precipitated and sol-gel silica, respectively. Our studying results reveal the formation of filler network constructed by the interconnecting of branched silica aggregates. And the silica with highly associated structure, pertaining to amorphous morphology, small size, and large surface area, presents short distance and effective molecular chain bridge between aggregates, thus forming strong and steady filler networks. This work would provide deep-seated revisiting of filler networks and corresponding reinforcement mechanism and offer guidance for optimizing the mechanical properties of silicone rubber.
A Synchrotron in situ X-ray Study on the Multiple Melting Behaviors of Isomorphous Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(P(HB-co-HV)) with Middle HV Content
Hao Zhu, You Lv, Dan Shi, Yi-Guo Li, Wei-Jun Miao, Zong-Bao Wang
2020, 38(9): 1015 -1024.   doi: 10.1007/s10118-020-2427-5
The multiple endothermic peaks without observable recrystallization phenomenon of isomorphous poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB-co-HV)] with the middle HV content of 19.4 mol% and 28.7 mol% were confirmed by differential scanning calorimetry (DSC), and the evolutions of crystal structure and lamellar morphology in the heating and melting process were tracked by in situ synchrotron wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) techniques. The emergence of asymmetric features of both the diffraction peaks and scattering curves indicates the coexistence of different lamellar crystals with varied unit cell parameters. Based on the in situ WAXD and SAXS measurements, we calculated the evolutions of the unit cell parameters a and b as well as the long period and lamellar thickness upon heating. The comparative analysis of WAXD and SAXS data confirms that the multiple endothermic peaks of P(HB-co-19.4%HV) and P(HB-co-28.7%HV) result from the melting of different lamellae rather than the melting/recrystallization. The thinner, unstable uniform lamellae with HV counits total inclusion melt first and the thicker, stable sandwich lamellae with HV counits partial inclusion melt last. In addition, the large second melting peak in P(HB-co-19.4%HV), differing from that of samples with HV content of 28.7 mol% and 36.2 mol%, is due to the unique state of HV content leading to a transition of sandwich lamellae to uniform lamellae. The present study establishes the relationship between the different lamellae structure and multiple melting behaviors of isomorphous copolymer.
Phase Separation in PCDTBT:PCBM Blends: from Flory-Huggins Interaction Parameters to Ternary Phase Diagrams
Monika Biernat, Paweł Dąbczyński, Paweł Biernat, Jakub Rysz
2020, 38(9): 1025 -1033.   doi: 10.1007/s10118-020-2424-8
The substantial increase in the efficiency of organic solar cells achieved in recent years would not have been possible without work on the synthesis of new materials and understanding the relationship between the morphology and performance of organic photovoltaic devices. The structure of solvent-cast active layers is a result of phase separation in mixtures of donor and acceptor components. To a large extent, this process depends on the interactions between the components of the mixture. Here, we present a systematic analysis of the morphology of poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) films in terms of the ternary phase diagram. The interaction parameters between PCDTBT and four different solvents, namely chloroform, chlorobenzene, o-dichlorobenzene, and toluene, were estimated based on swelling experiments. Based on these values, ternary phase diagrams of PCDTBT:PC70BM in different solvents were calculated. The morphology of spin-coated films with different blend ratios cast from different solvents is discussed in terms of the obtained phase diagrams.
Differences in Crystallization Behaviors between Cyclic and Linear Polymer Nanocomposites
Rong-Juan Liu, Zhi-Ping Zhou, Yong Liu, Zhao-Peng Liang, Yong-Qiang Ming, Tong-Fan Hao, Yi-Jing Nie
2020, 38(9): 1034 -1044.   doi: 10.1007/s10118-020-2403-0
Cyclic polymers exhibit fascinating crystallization behaviors owing to the absence of chain ends and more compact conformations. In the current simulation, dynamic Monte Carlo simulations were performed to reveal the underlying mechanism of the effect of chain topology and chain length on crystallization of polymer in solutions containing one-dimensional nanofiller. Simulation results suggested that the filled cyclic polymers exhibit higher melting temperature, higher crystallization temperature, and faster crystallization rate than the analogous linear polymers of identical chain length, especially in the systems with relatively short chains. Based on the Thomson-Gibbs equation, we theoretically analyzed the difference in the melting point between the cyclic and linear polymers under different chain lengths, and derived the dependence of the ratio of the melting point of the linear polymers to that of its cyclic analogs on chain length. In addition, it was also observed that the nanofiller can induce the formation of nanohybrid shish-kebab structure during isothermal crystallization of all systems.
Correction to “Mediating the Migration of Mesenchymal Stem Cells by Dynamically Changing the Density of Cell-selective Peptides Immobilized on β-Cyclodextrin-modified Cell-resisting Polymer Brushes”
Wang Du, De-Teng Zhang, Xue-Mei Wang, Tan-Chen Ren, Chang-You Gao
2020, 38(9): 1045 -1046.   doi: 10.1007/s10118-020-2469-8