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Polyether-polyester and HMDI Based Polyurethanes: Effect of PLLA Content on Structure and Property
Lei Shi, Ruo-Yu Zhang, Wu-Bin Ying, Han Hu, Yu-Bin Wang, Ya-Qian Guo, Wen-Qin Wang, Zhao-Bin Tang, Jin Zhu
Corrected proof , doi: 10.1007/s10118-019-2283-3
[Abstract](102) [FullText HTML](17) [PDF 1235KB](7)
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Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4′-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by a two-step reaction, and the morphology and property of the resultant TPU could be adjusted by varying the PLLA contents. The soft segment was composed of PLLA and PTMG diols. By controlling the percentage of PLLA in the soft segment, the glass transition temperature and mechanical properties of the polyurethanes could be regulated. Based on the FTIR spectrum, we found that two kinds of hydrogen bonding existed individually in soft matrix and hard domain. The hydrogen bonding in soft matrix was unstable, which could be destroyed during elongation. With in situ stretching WAXS and SAXS experiments, we found that the PLLA crystal was destroyed and the PLLA domain oriented along the stretch direction. Finally, we proposed a schematic model to illustrate the microstructures of these elastomers before and after stretch.
Synthesis of Polycarbonate Block Terpolymers Using Robust Cobalt Catalyst Systems
Ying-Jie Jiang, Wei-Min Ren, Ye Liu, Xiao-Bing Lu
Corrected proof , doi: 10.1007/s10118-019-2270-8
[Abstract](31) [FullText HTML](20) [PDF 730KB](2)
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This contribution reports an efficient approach for preparing polycarbonate block terpolymers by immortal stepwise copolymerization of CO2 with different epoxides in the presence of enol chain transfer, mediated by robust cobalt catalyst systems consisting of the fluorine substituted salenCo(III)NO3 or biphenol-linker bimetallic Co(III) complex in conjunction with an ionic cocatalyst, PPNX (PPN = bis(triphenylphosphine)iminium, X = NO3 or 2,4-dinitrophenoxide). Various polycarbonate block terpolymers were obtained in perfectly unimodal distribution of their molecular weights with narrow polydispersity. They all possessed only one broad glass transition temperature, which could be adjusted by altering the length of different polycarbonate segments.
Preparation of Three Dimensional Hydroxyapatite Nanoparticles/Poly(vinylidene fluoride) Blend Membranes with Excellent Dye Removal Efficiency and Investigation of Adsorption Mechanism
Jian-Hua Li, Hui Zheng, Hua-Xiang Lin, Bo-Xin Zhang, Jia-Bin Wang, Tong-Lei Li, Qi-Qing Zhang
Corrected proof , doi: 10.1007/s10118-019-2271-7
[Abstract](48) [FullText HTML](31) [PDF 1643KB](2)
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In this work, poly(vinylidene fluoride) (PVDF) membranes with hydrophilicity as well as preeminent mechanical strength and dye removal efficiency were fabricated by blending with three dimensional hydroxyapatite nanoparticles (HAPNPs). Surface chemical composition and morphology of the prepared membranes were systematically investigated by ATR-FTIR, XPS, XRD, FESEM, and EDS mapping analyses. The results verified that a large number of HAPNPs were successfully embedded on the modified membrane cross-sections. Moreover, HAPNPs content in the casting solution is an important factor that could have profound influence on the structures and performances of PVDF/HAPNPs blend membranes. The optimal membrane M2 with 2 wt% HAPNPs exhibited excellent hydrophilicity, outstanding mechanical strength of 19.60 MPa, and high water flux of (2466 ± 31) L·m–2·h–1. The maximum static adsorption capacity of the optimal membrane was about 10.83 mg/g, which is 3.75 times that of the pristine PVDF membrane (2.89 mg/g). PVDF/HAPNPs membranes were not only utilized for static adsorption, but also applied to dynamic dye removal. The possible adsorption mechanism between Congo red (CR) and HAPNPs embedded on the blend membranes was firstly discussed in this work. HAPNPs interacted with CR via Lewis reaction, hydrogen bond interaction, as well as electrostatic attraction to achieve the adsorption effect. Herein, the PVDF/HAPNPs blend membranes with extraordinary hydrophilicity, mechanical strength, and dye removal efficiency possess tremendous potential for practical applications of wastewater treatment.
Effects of Main-chain and Chain-ends on the Organogelation of Stearoyl Appended Pendant Valine Based Polymers
Mridula Nandi, Swagata Pan, Dipannita Ghosh, Priyadarsi De
Corrected proof , doi: 10.1007/s10118-019-2265-5
[Abstract](117) [FullText HTML](32) [PDF 908KB](7)
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In this work, we investigated the effect of hydrophobic interactions between the polymeric backbone and chain-end groups on the self-assembly pathway of stearoyl appended side-chain valine (Val)-based poly(methacrylate/acrylate) homopolymers in different organic hydrocarbons. Gelation studies conducted revealed that while polymers with polyacrylate as backbone induces gelation in several organic hydrocarbons, polymers with polymethacrylate in the main-chain significantly hinders macroscopic gelation. Morphology of the organogels was analysed by field emission scanning electron microscopy (FESEM), and mechanical strengths of the organogels were determined by rheological measurements. Reversible addition-fragmentation chain transfer (RAFT) polymerization chain transfer agents (CTA)s, [R1―S―C=(S)―S―R2] with different ―R1 and ―R2 groups, have been employed to study the effect of structural variation at the chain-end on macroscopic assembly mechanism. We found that the additional interactions between terminal groups via hydrogen-bonding or π-π stacking interactions or both help to build up the self-assembly pathway and thereby produces mechanically stable organogels.
The Effect of Reaction Conditions on the Synthesis of Thermoplastic Elastomers Containing Polyalloocimene, Polyisobutylene and Tapered Blocks
Jozsef Kantor, Judit E Puskas, Gabor Kaszas
Corrected proof , doi: 10.1007/s10118-019-2254-8
[Abstract](119) [FullText HTML](69) [PDF 783KB](9)
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This work investigates the effect of reaction conditions on the copolymerization of isobutylene (IB) with alloocimene (Allo) in methyl chloride (MeCl) using AlCl3 and ethylaluminum dichloride (EtAlCl2) as coinitiators and adventitious moisture as the initiator. Both AlCl3 and EtAlCl2 produced high molecular weight (Mn > 1.0 × 105 g/mol) thermoplastic elastomers (TPEs) with good mechanical properties in short reaction time (< 10 min). These unique TPEs have unsaturations in the end blocks, leading to easy functionalization and/or crosslinking.
Preparation and Characterization of Multi-layer Poly(arylene sulfide sulfone) Nanofibers Membranes for Liquid Filtration
Zhen-Yan Liu, Zhi-Mei Wei, Xiao-Jun Wang, Gang Zhang, Sheng-Ru Long, Jie Yang
Corrected proof , doi: 10.1007/s10118-019-2280-6
[Abstract](92) [FullText HTML](34) [PDF 3759KB](10)
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Owing to the excellent filtration performance and low energy cost, polymeric nanofibers microfiltration (MF) membranes have attracted increasing attentions. Poly(arylene sulfide sulfone) (PASS), as one of the structurally modified polymers based on poly(phenylene sulfide) (PPS), has been selected as the raw material to fabricate nanofibers MF membranes via electrospun techniques. The effects of PASS solution and the electrospinning processing parameters on the structural morphology of nanofibers were investigated in detail. The average diameter of PASS nanofibers was (296 ± 46) nm under the optimal condition: polymer concentration of 0.27 g·mL–1 PASS/DMI, applied voltage of 20 kV, and speed of collector drum of 300 r·min–1. And then the multi-layer PASS nanofibers MF membranes were fabricated from cold-pressing the optimized PASS nanofibers (as-prepared PASS nanofibers) membrane. The morphology, porosity, pore size, mechanical properties, and surface wettability of the multi-layer PASS nanofibers MF membranes could be tuned by the layers of as-prepared nanofibers membrane. The results demonstrated that the membrane with 6 layers (marked as PASS-6) exhibited the smallest porosity, smallest pore size, highest mechanical property, and best surface wettability. Meanwhile, the multi-layer PASS nanofibers MF membranes showed that the rejection ratio gradually increased, while the pure water flux decreased with increasing membranes thickness. The PASS-6 membrane exhibited large water flux of 747.76 L·m–2·h–1 and high separation efficiency of 99.9% to 0.2 μm particles, making it a promising candidate for microfilter.
Mechanical Properties of Interlocked-ring Polymers: A Molecular Dynamics Simulation Study
Zheng-Tao Wu, Jia-Jia Zhou
Corrected proof , doi: 10.1007/s10118-019-2279-z
[Abstract](103) [FullText HTML](16) [PDF 767KB](10)
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Interlocked-ring polymers, also known as polycatenanes, possess an interesting molecular architecture. These polymers are composed of many interlocked rings in a linear chain. The topological constrain between neighboring rings distinguishes the interlocked-ring polymer from its linear counterpart. Here we present extensive molecular dynamic simulations on the interlocked-ring polymers and analyze the static properties of the polymer. By applying external forces to the polymer, we also study the force-extension curves of the polymer, which provides rich information about the mechanical properties of the interlockedring polymers.
Dimethylacetamide-promoted Direct Arylation Polycondensation of 6,6′-Dibromo-7,7′-diazaisoindigo and (E)-1,2-bis(3,4-difluorothien-2-yl)ethene toward High Molecular Weight n-Type Conjugated Polymers
Kai Guo, Yu Jiang, Ying Sui, Yun-Feng Deng, Yan-Hou Geng
Corrected proof , doi: 10.1007/s10118-019-2277-1
[Abstract](83) [FullText HTML](6) [PDF 689KB](3)
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A highly efficient and eco-friendly protocol for the synthesis of an alternating copolymer poly(7,7′-diazaisoindigo-alt-(E)-1,2-bis(3,4-difluorothien-2-yl)ethene) (PAIID-4FTVT) via direct arylation polycondensation (DArP) is presented. Through detailed study, we found that the inhibitory effect of 7,7′-diazaisoindigo on DArP stemmed from the coordination of N atom with catalyst can be overcome by using dimethylacetamide (DMAc) as the co-solvent. Thus, PAIID-4FTVT with number-average molecular weight (Mn) > 100 kDa was synthesized via DArP by optimizing the content of DMAc. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy revealed that PAIID-4FTVT was defect-free. Top gate and bottom contact (TG/BC) organic thin-film transistors (OTFTs) were fabricated to characterize the semiconducting properties of the polymers. PAIID-4FTVT displayed unipolar n-type characteristics with the electron mobility (μe) strongly dependent on Mn. The highest μe up to 0.25 cm2·V–1·s–1 was achieved with the high molecular weight sample.
Co-delivery of Doxorubicin and Afatinib with pH-responsive Polymeric Nanovesicle for Enhanced Lung Cancer Therapy
Heng-Ye Gong, Yan-Gui Chen, Xing-Su Yu, Hong Xiao, Jin-Peng Xiao, Yong Wang, Xin-Tao Shuai
Corrected proof , doi: 10.1007/s10118-019-2272-6
[Abstract](112) [FullText HTML](10) [PDF 839KB](8)
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Drug-resistance and drastic side effects are two major issues of traditional chemotherapy which may result in trail failure even death. Nanoparticle-mediated multidrug combination treatment has been proven to be a feasible strategy to overcome these challenges. In the present study, amphipathic block polymer of methoxyl poly(ethylene glycol)-poly(aspartyl(dibutylethylenediamine)-co-phenylalanine) (mPEG-P(Asp(DBA)-co-Phe)) was synthesized and self-assembled into pH-responsive polymeric vesicle. The vesicle was utilized to co-deliver cancer-associated epidermal growth factor (EGFR) inhibitor of afatinib and DNA-damaging chemotherapeutic doxorubicin hydrochloride (DOX) for enhanced non-small-cell lung cancer (NSCLC) therapy. As evaluated in vitro, the pH-responsive design of nanovesicle resulted in a rapid release of encapsulated drugs into tumor cells and caused enhanced cell apoptosis. In addition, in vivo therapeutic studies were conducted and the results evidenced that the co-delevery of DOX and afatinib using pH-sensitive nanovector was a promising strategy for NSCLC treatment.
Inhomogeneous Natural Network Promoting Strain-induced Crystallization: A Mesoscale Model of Natural Rubber
Han Liu, Guang-Su Huang, Lai-Yun Wei, Jian Zeng, Xuan Fu, Cheng Huang, Jin-Rong Wu
Corrected proof , doi: 10.1007/s10118-019-2267-3
[Abstract](92) [FullText HTML](13) [PDF 1477KB](1)
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Although synthetic rubbers show continuously improved mechanical properties, natural rubber (NR) remains irreplaceable in the rubber family due to its superior mechanical properties. A mainstream viewpoint regarding the superiority of NR is that NR possesses a natural network formed by linking the poly(cis-1,4-isoprene) chain terminals to protein and phospholipid aggregates; after vulcanization, the natural network additionally contributes to rubber mechanics by both increasing the network density and promoting the strain-induced crystallization (SIC) behavior. However, the reason why the natural network promotes SIC is still unclear; in particular, only using the increased network density cannot explain our finding that the NR shows smaller onset strain of SIC than Gel (the gel component of NR with higher network density) and even vulcanized NR. Herein, we point out that the inhomogeneous chain deformation is the alternative reason why SIC of NR takes place at smaller strain than that of Gel. More specifically, although the natural network is homogenous on the subchain length scale based on the proton double-quantum NMR results, it is essentially inhomogeneous on mesoscale (100 nm), as revealed by the small angle X-ray scattering analysis. This inhomogeneous network also leads to the mesoscale deformation inhomogeneity, as detected by the orientation of stearic acid (SA) probe, thus resulting in the smaller onset strain of SIC of NR. Based on the experimental results, a mesoscale model is proposed to qualitatively describe the crucial roles of inhomogeneous structure and deformation of natural network in NR’s mechanical properties, providing a clue from nature to guide the development of high-performance rubbers with controlled structures at mesoscale.
Synthesis and Properties of Reversible Disulfide Bond-based Self-healing Polyurethane with Triple Shape Memory Properties
Han Jia, Kun Chang, Shu-Ying Gu
In press , doi: 10.1007/s10118-019-2268-2
[Abstract](114) [FullText HTML](25) [PDF 1230KB](10)
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A reversible disulfide bond-based self-healing polyurethane with triple shape memory properties was prepared by chain extending of random copolymer poly(lactide-co-caprolactone) (PCLA), hexamethylene diisocyanate (HDI), polytetrahydrofuran (PTMEG), and 4,4′-aminophenyl disulfide. The chemical structures were characterized using 1H nuclear magnetic resonance (1H-NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). The thermal properties, self-healing properties, triple-shape memory effect, and quantitative shape memory response were evaluated by differential scanning calorimetry (DSC), tensile tests, two-step programming process thermal mechanical experiments, and subsequent progressive thermal recovery. The self-healing mechanism and procedures were investigated using polarizing optical microscopy (POM) and an optical profiler. It was concluded that self-healing properties (up to 60%) and triple-shape memory properties around 35 and 50 °C (with shape fixation ratios of 94.3% and 98.3%, shape recovery ratios of 76.6% and 85.1%, respectively) were integrated to the shape memory polyurethane. As-prepared polyurethane is expected to have potential applications in multi-shape coatings, films, and step-by-step deploying structures.
Miscibility and Crystallization Behavior of Novel Branched Poly(ethylene succinate)/Poly(vinyl phenol) Blends
Kang-Jing Zhang, Zhao-Bin Qiu
Corrected proof , doi: 10.1007/S10118-019-2269-1
[Abstract](119) [FullText HTML](27) [PDF 759KB](12)
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The blends of novel branched poly(ethylene succinate) (b-PES) and poly(vinyl phenol) (PVPh) were prepared via a solution and casting method. The miscibility, melting behavior, spherulitic morphology and growth, and crystal structure of b-PES/PVPh blends were investigated in detail. PVPh was miscible with b-PES over the whole compositions as evidenced by the single composition dependent glass transition temperature. Double melting behavior occurred in neat b-PES and b-PES/PVPh 85/15 blend after isothermal melt crystallization, which may be explained by the melting, recrystallization, and remelting mechanism. In addition, the depression of equilibrium melting point of an 85/15 blend was also found, confirming again the miscibility between the two components. The addition of PVPh caused the decrease of nucleation density and crystal growth rates of b-PES spherulites in the blend. The crystal structure of b-PES was unchanged before and after blending; moreover, the crystallinity of b-PES decreased slightly in the blend.
Analysis of Dimer Impurity in Polyamidoamine Dendrimer Solutions by Small-angle Neutron Scattering
Tian-Fu Li, Yi-Yun Cheng, Yu Wang, Hui Wang, Dong-Feng Chen, Yun-Tao Liu, Li Zhang, Wen-Ze Han, Rong-Deng Liu, Zi-Jun Wang, Chun-Ming Yang, Charl J. Jafta, Daniel Clemens, Uwe Keiderling
Corrected proof , doi: 10.1007/s10118-019-2260-x
[Abstract](158) [FullText HTML](68) [PDF 573KB](11)
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Dimer impurity in the solution of a generation five (G5) polyamidoamine (PAMAM) dendrimer has been investigated by small-angle neutron scattering (SANS). The existence of dimer impurity in dendrimer solution was evidenced by indirect Fourier transform (IFT) analysis of the SANS data, in which the maximum dimension of particles in solution was found to be about twice the diameter of G5 dendrimer. We then developed an analytical model which accounts for the scattering contribution from both dendrimer monomer and dimer. The experimental data were well fitted by using the established model. The results showed that the amount of dimer impurities is significant for the measured three batches of G5 PAMAM dendrimers.
Optimization of Ethylene Glycol Doped PEDOT:PSS Transparent Electrodes for Flexible Organic Solar Cells by Drop-coating Method
Hui-Qin Cui, Rui-Xiang Peng, Wei Song, Jian-Feng Zhang, Jia-Ming Huang, Li-Qiang Zhu, Zi-Yi Ge
Corrected proof , doi: 10.1007/s10118-019-2257-5
[Abstract](167) [FullText HTML](78) [PDF 661KB](14)
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Fabrication of flexible transparent electrodes (FTEs) is one of the core technologies in the field of flexible electronics. Among multiple choices of FTEs, poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonic acid) (PEDOT:PSS) has shown its promising application in roll-to-roll manufacturing. A simple yet effective method for substantially boosting the conductivity of these conducting polymer films without causing large-domain aggregations is by adding ethylene glycol (EG) as dopant. Herein, we investigated in detail the effects of the secondary solvent of ethylene glycol (EG) on the optical and electrical characteristics of PEDOT:PSS films. The modified PEDOT:PSS FTEs were deposited using drop-coating techniques as it had greater compatibility for large-area samples than the conventional spin-coating method did. The 6% EG-doped PEDOT:PSS FTE via drop-coating method achieved a high figure of merit (FoM) value of 47.24 and the devices fabricated using the optimal PEDOT:PSS FTE yielded a high power conversion efficiency (PCE) of 8.89%, mostly attributed to the modified PEDOT:PSS films that had excellent optical and electrical characteristics with low surface roughness. These results suggested that EG-doping could effectively boost the conductivity of PEDOT:PSS films and that the modified PEDOT:PSS FTE is suitable for roll-to-roll manufacturing in the future.
Crystallization and Phase Behavior in Block Copolymer Solution: An in Situ Small Angle X-ray Scattering Study
Hong-Yan Zhu, Feng Tian, Xiu-Hong Li, Hui-Bin Qiu, Jie Wang
Corrected proof , doi: 10.1007/s10118-019-2258-4
[Abstract](156) [FullText HTML](84) [PDF 1101KB](28)
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Amphiphilic diblock copolymers self-assemble into a variety of micellar structures with diverse shapes in selective solvents. Here, we study the concentration and temperature dependence of the packing structure of spherical micelles of a polyisoprene-b-poly(2-vinylpyridine) (PI-b-P2VP) diblock copolymer in toluene using synchrotron radiation small angle X-ray scattering (SR-SAXS) and atomic force microscopy (AFM) techniques. Randomly packed spherical micelles are detected in dilute solutions, while in concentrated solutions, face-centered cubic (FCC), body-centered cubic (BCC) mixed crystal structures, and pure BCC crystal structures are observed with an increase in concentration. In situ SAXS experiments on the FCC/BCC mixed crystal structures reveal a novel FCC/BCC → BCC → Disorder → BCC phase behavior during the thermal annealing process. These results demonstrated that the BCC phase is apparently more stable than the FCC phase in the current sphere-packing system and FCC/BCC is a metastable state. The incompatibility of the PI and P2VP blocks decreases at a higher temperature and renders the variation of domain spacing.
Preparation and Properties of Ultrathin Flexible Expanded Graphite Film via Adding Natural Rubber
Yan-Ling Mo, Yu-Xin Tian, Yu-Hang Liu, Feng Chen, Qiang Fu
Corrected proof , doi: 10.1007/s10118-019-2264-6
[Abstract](125) [FullText HTML](34) [PDF 921KB](19)
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Expanded graphite (EG) films exhibit potential use in a wide field including thermal management, conductive applications, and electromagnetic interference (EMI) shielding. However, their poor tensile strength and brittleness are crucial deficiencies for commercial applications. To address these defects, in our work, natural rubber (NR) is employed to improve EG films for better mechanical strength and flexibility. The origin of the strengthening effect of EG films by the addition of natural rubber mainly arises from the formation of a simulate shell structure. Compared to the neat EG films, the addition of merely 2 wt% NR can give rise to superior ductility. Further, the loading of 10 wt% NR realizes a significant mechanical enhancement of the EG/NR films, i.e., 2.4 and 11.4 times increase in tensile strength and elongation at break, respectively. Besides, EG/NR films containing 10 wt% NR can still sustain excellent thermal and electric conductivities of 173 W·m−1·K−1 and 75 S·cm−1, respectively. Furthermore, a very high EMI of 41.4 dB is achieved as the film thickness reaches 50 μm. Thus, the lightweight EG/NR films with comprehensive performance as well as their virtue of green and simple large-scale preparation endow them with the possibility of designing next-generation flexible electronics.
Cu(0) Wire-mediated Single-electron Transfer-living Radical Polymerization of Oligo(ethylene oxide) Methyl Ether Acrylate by Selecting the Optimal Reaction Conditions
Liang Ding, Juan Li, Rui-Yu Jiang, Ling-Fang Wang, Wei Song, Lei Zhu
Corrected proof , doi: 10.1007/s10118-019-2263-7
[Abstract](130) [FullText HTML](21) [PDF 1080KB](6)
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The efficient Cu(0) wire-catalyzed single-electron transfer-living radical polymerization (SET-LRP) in organic solvents and mixtures of the organic solvents with water has been thoroughly investigated. Oligo(ethylene oxide) methyl ether acrylate was used as an exemplar oligomer monomer to determine the optimum polymerization conditions for rapid, controlled, and quantitative production of well-defined polymers. The effects of Cu(0)-wire length (12.5 or 4.5 cm), ligand type (tris(dimethylaminoethyl)amine, Me6-TREN, or tris(2-aminoethyl)amine, TREN), and solvent type (dipolar aprotic solvents, cyclic ethers, alcohol, or acetone) on the polymerization have been evaluated. Kinetic experiments were performed for all polymerizations to assess the " living” behavior of each system employed. Importantly, TREN could be used as a replacement for Me6-TREN in Cu(0) wire-catalyzed SET-LRP of oligomer monomer, which probably provides the most economical and efficient methodology since TREN is 80 times less expensive than Me6-TREN. The high chain-end fidelity of resulting polymer was experimentally verified by thiol-Michael addition reaction at the α-Br chain end and subsequent chain extension with methyl acrylate.
Synthesis of Cerium-containing Polymethylphenyl Silicone and Its Antioxidant Effect on Fluorosilicone Rubber
Yong Guan, Jian Hu, Yong-Kang Huang, Yang You, Huan-Yao Zhang, An-Na Zheng, Xiang Xu, Da-Fu Wei
Corrected proof , doi: 10.1007/s10118-019-2266-4
[Abstract](109) [FullText HTML](53) [PDF 742KB](3)
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As an essential elastomer used in edge technologies, fluorosilicone rubber (FSR) suffers serious oxidative ageing problem when serving at high temperature. Cerium oxide is generally used as an antioxidant additive but remains unsatisfactory. In order to obtain better antioxidant effect on improving the thermal stability of FSR, a kind of cerium-containing polymethylphenyl silicone (PSI-Ce) was synthesized and the structure was verified by Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR). Due to the homogeneous dispersion on molecular scale, PSI-Ce imposed much better antioxidant effect than the commercial CeO2 did, no matter from isothermal degradation at 320 °C or thermal-oxidative ageing test at 230 °C. In particular, after ageing for 72 h, FSR/PSI-Ce (2 phr) maintained 82% of tensile strength and 63% of elongation at break, in comparison to the corresponding values of 48% and 42% for FSR/CeO2 (2 phr). Moreover, 2 phr PSI-Ce was equivalent to 0.046 phr CeO2 according to cerium element conservation.
Synthesis and Physico-chemical Properties of (Co)polymers of 2-[(2E)-1-methyl-2-buten-1-yl]aniline and Aniline
A. Andriianova, A. Shigapova, Y. Biglova, R. Salikhov, I. Abdrakhmanov, A. Mustafin
Corrected proof , doi: 10.1007/s10118-019-2261-9
[Abstract](111) [FullText HTML](57) [PDF 1046KB](15)
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A new soluble polymer on 2-[(2E)-1-methyl-2-buten-1-yl]aniline and its copolymers with aniline basis have been synthesized in various molar ratios. For all samples, the electrical conductivity, morphology, solubility, electrochemical properties, as well as spectral and molecular mass characteristics have been studied, and a comparative analysis with polyaniline has been carried out. The substituent introduced into the aniline aromatic ring significantly improves the solubility in typical organic solvents of a high molecular weight product. The morphology of the test compounds depends on the co-monomer ratio. As the content of the substituted aniline in the initial mixture increases, the morphology of the polymer changes from the inherent polyaniline fibrous microstructure to the globular one with irregular substituted polyaniline shapes and sizes. Electrochemical study of the samples revealed that the higher the oxidation potential, the wider the band gap (ranging from 2.00 to 2.15). The electrical conductivity decreases in proportion to the increase in the substituted aniline concentration of the initial co-monomer mixture and amounts to 12.5–35.7 × 106 nSm.
Ultrafast Form II to I Transition of Isotactic Polybutene-1
Xing Qiu, Umair Azhar, Jing-Qing Li, Ding-Hai Huang, Shi-Chun Jiang
Corrected proof , doi: 10.1007/s10118-019-2273-5
[Abstract](237) [FullText HTML](97) [PDF 473KB](35)
Abstract:
Isotactic polybutene-1 (iPB-1) is a semi-crystalline polymer with polymorph and puzzled structural transitions. The stable form I of iPB-1 with excellent physical and mechanical properties can hardly be obtained directly from the melt; instead, metastable form II will spontaneously and slowly transform into form I. Bypassing the unstable form II formation is of great significance in polymer processing, which inspires extensive research on seeking the pathways to direct formation of form I. Methods for accelerating form II to I transition are another main focus in terms of practical approach for directly obtaining form I. Taking advantage of the solvent, an ultrafast transition of iPB-1 from form II to I within minutes has been achieved at room temperature. Such an ultrafast transition is detected after treating with dichloromethane (DCM) at 30 °C, though the framework of isothermally crystalized iPB-1 spherulite morphology could not be fully modified. The ultrafast II-I transition of iPB-1 is attributed to the solvent-induced packed-mesophase and temperature-selected chain conformation adjustment.This ultrafast transition would shed light on understanding the mechanisms of polymorphic transitions in iPB-1.
Ultrasmall Nanoparticles Diluted Chain Entanglement in Polymer Nanocomposites
Sheng-Chao Chai, Tian-Yang Xu, Xiao Cao, Gang Wang, Quan Chen, Hao-Long Li
Corrected proof , doi: 10.1007/s10118-019-2262-8
[Abstract](324) [FullText HTML](133) [PDF 2661KB](58)
Abstract:
Nanoparticle-polymer composites exhibit unusual mechanical properties and chain dynamics when the nanoparticle size is smaller than the entanglement mesh size of the matrix polymer chains, corresponding to the ultrasmall regime defined by de Gennes. However, the mechanism is still ambiguous due to the lack of suitable model systems. Here, we develop an ultrasmall nanoparticle system by using a bimodal grafting strategy to graft both short alkyl chains and long polystyrene chains onto the polyoxometalate molecular nanoparticles with a tunable repulsive potential between the nanoparticles, thus facilitating their uniform dispersion in polystyrene matrices. Linear viscoelasticity of the resultant nanocomposites changes with increasing the filler content, which shows a decrease in both plateau modulus and terminal relaxation time, indicative of a dilution effect of the nanoparticles. Namely, the entanglement network becomes sparser with increasing the filler content.
Using an Inhibitor to Prevent Plasticizer Migration from Polyurethane Matrix to EPDM Based Substrate
Hadi Rezaei-Vahidian, Tohid Farajpour, Mahdi Abdollahi
Corrected proof , doi: 10.1007/s10118-019-2251-y
[Abstract](179) [FullText HTML](105) [PDF 933KB](6)
Abstract:
The loss of adhesion between the propellant and insulator is one of the most important problems in solid propellant motors due to migration of plasticizer to interface of propellant and insulator. In this work, the polyurethane (PU) binder containing DOP plasticizer was used as a polymeric matrix and β-cyclodextrin (β-CD) was applied as inhibitor agent to prevent plasticizer migration from the PU matrix into the ethylene propylene diene monomer (EPDM) substrate. To increase the compatibility of β-CD and PU matrix, a derivative of β-CD has been synthesized using toluene diisocyanate (β-CD-TDI). The synthesized derivative was characterized by MALDI-MS and FTIR-ATR analyses. FTIR-ATR results confirmed the formation of bonding between β-CD and the polymeric network while the MALDI-MS results showed that the synthesized derivative contained two β-CD and 7 TDI molecules bonded to β-CD. Investigation of the mechanical properties of PU modified by β-CD-TDI showed a decrease in tensile strength and an increase in elongation at break with increasing β-CD-TDI content. DMTA results showed a decrement in crosslinking density by increasing the β-CD-TDI content. Also, to investigate plasticizer migration, extraction of the DOP plasticizer from samples was performed using dichloromethane solvent and its concentration was measured by gas chromatography. The results of migration evaluation after four months showed that using β-CD as an inhibitor agent in the PU binder could prevent the migration of plasticizer to EPDM substrate.
Increasing the Content of β Phase of Poly(9,9-dioctylfluorene) by Synergistically Controlling Solution Aggregation and Extending Film-forming Time
Ya-Di Liu, Qiang Zhang, Xin-Hong Yu, Jian-Gang Liu, Yan-Chun Han
Corrected proof , doi: 10.1007/s10118-019-2259-3
[Abstract](213) [FullText HTML](123) [PDF 782KB](26)
Abstract:
For poly(9,9-dioctylfluorene) (PFO), β phase (coplanar conformation with the intra-chain torsion angle of 165°) has a greater conjugation length and higher degree of order compared to those of α phase, which favors charge carrier transport. However, the highest content of β phase obtained so far is 45%. We propose to increase the content of β phase by promoting the solution aggregation of PFO molecules and extending film-forming time. For this purpose, 1,8-diiodooctane (DIO) is added to PFO o-xylene solution, which enhances the interaction of PFO chains and improves the planarity of PFO backbone, resulting in the formation of ordered aggregation. The aggregates act as nucleation centers to promote the formation of β phase. The content of β phase increases with increasing DIO concentration and reaches a platform of 39% as DIO is more than 4 vol%. Furthermore, the film is kept in a sealed environment with o-xylene atmosphere for 3 h, thus the PFO molecules have enough time to diffuse to the crystallization front and achieve disorder-order transition. As a result, the crystallinity of PFO is improved significantly and the content of β phase increases to 52%, reaching the highest value reported so far.
Controllable Emission via Tuning the Size of Fluorescent Nano-probes Formed by Polymeric Amphiphiles
Xiao-Cheng Wang, Shi-Xin Zhou, Lan Ding, Yu-Han Zhao, Shen-Xi Min, Bin Dong, Bo Song
Corrected proof , doi: 10.1007/s10118-019-2256-6
[Abstract](204) [FullText HTML](123) [PDF 785KB](32)
Abstract:
Incorporating fluorophores into polymeric nanoparticles has been testified as a feasible way to improve the emitting property and bio-compatibility of nano-emitters, which can be applied as fluorescent probes in labeling cells for imaging. Plenty of efforts have been made on the above direction. However, the size effect of nano-emitters has not been addressed yet mainly given the difficulties in controlling morphology and size of the assemblies. In our preceding study, we employed post-polymerization modification method for preparing amphiphilic copolymers, and obtained core-shell (the hydrophobic fluorophores are wrapped inside the nanoparticle to form the core) assemblies in aqueous solution. By this method, we are able to regulate the ratio of the hydrophilic/hydrophobic moieties, and thus alternate the size of the assemblies in a rather simple way. In this study, we synthesized a series of random copolymers by changing the ratio of poly(ethylene glycol) to tetraphenylethylene groups. Notably, the number of repeating units of the polymer was controlled constant for all the copolymers. The self-assembly of these copolymers resulted in different sizes of nanoparticles, and the size decreased with the decreasing fraction of poly(ethylene glycol). Interestingly, the emission of the nanoparticles showed size dependence, and smaller diameter corresponded to stronger emission. Being cultured with HeLa cells, either the large (diameter of ~300 nm) or the small (diameter of ~180 nm) nano-emitters allowed for very high cell viabilities up to 25 μg·mL−1. Both of them can be applied in cell imaging and provide high contrast fluorescent images.
Fabrication of 6FDA-HFBAPP Polyimide Asymmetric Hollow Fiber Membranes and Their CO2/CH4 Separation Properties
Cong-Jun Gan, Xiao-Chen Xu, Xue-Wei Jiang, Feng Gan, Jie Dong, Xin Zhao, Qing-Hua Zhang
Corrected proof , doi: 10.1007/s10118-019-2255-7
[Abstract](192) [FullText HTML](116) [PDF 1269KB](11)
Abstract:
In this work, poly(amide acid) solution, the precursor of polyimide, was synthesized by the reaction of 4,4′-(hexafluoroisopropylidene)diphthalicanhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropanane in the solvent of N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF). Then, hollow fiber membranes for high flux gas separation were prepared by dry-jet wet spinning using the precursor solution of poly(amide acid) as the spinning dope and a subsequent imidization process. Silicone rubber was further coated outside the obtained hollow fiber membranes to repair the defects on the denser layer. The effects of internal, external coagulation bath ratios with air gap, and coating solution concentrations on the morphologies, structures, and separation performance of the membranes were studied. Results showed that the sponge-like support layer was formed when the content of NMP was increased from 50% to 90% in the internal coagulation bath. The outer surface of the membrane became denser when the water content in the external coagulation bath increased from 40% to 100%, and the separation coefficient of CO2/CH4 increased by 2 times. This value could reach up to 1.4 when the air gap was 6 cm. With tuning the mass fraction of silicone rubber as 5%, hollow fiber composite membranes with uniform coating layer and an improved separation coefficient of 5.4 could be obtained.
Amphiphilic Dendrimer-like Copolymers with High Chain Density by Living Anionic Polymerization
Ke Zheng, Jun-Po He
Corrected proof , doi: 10.1007/s10118-019-2247-7
[Abstract](244) [FullText HTML](85) [PDF 2749KB](16)
Abstract:
We report here a method for the preparation of amphiphilic dendrimer-like copolymers with dendritic polystyrene (PS) core and protonated poly(2-vinyl pyridine) (P2VP) or poly(methacrylic acid) (PMAA) shell. The method employed the efficient coupling reaction of anionic living polymer chains and chlorosilane. The synthesis started from a functionalized 3rd generation dendritic polystyrene, G3PS-g-SiCl, used as the precursor. The dendrimer-like copolymer of styrene and 2-vinyl pyridine, G3PS-g-P2VP, was synthesized by direct coupling of living P2VPLi to the precursor. The dendrimer-like copolymer of styrene and tert-butyl methacrylate, G3PS-g-PtBMA, was synthesized by an indirect procedure in which a living polymer containing mainly PtBMA segment was attached to the precursor. Both methods resulted in the formation of dendrimer-like copolymers with the high molecular weights (up to 8.5 × 106 Da), large molecular sizes (diameter up to 73 nm), and dense shells (number of arms up to 1300). These products, G3PS-g-P2VP and G3PS-g-PtBMA, were protonated with trifluoroacetic acid and acidic hydrolyzed, respectively. After transformation, amphiphilic dendrimer-like copolymers, G3PS-g-P2VPH+ and G3PS-g-PMAA, were obtained. Preliminary results on the solution properties of the amphiphilic products were presented.
Controlling Heat Transfer for the Manufacturing of High Molecular Weight Polyisobutylene via Formation of Micelles
Szilard Csihony, Nicole Janssen, Klaus Mühlbach
Corrected proof , doi: 10.1007/s10118-019-2250-z
[Abstract](179) [FullText HTML](99) [PDF 553KB](19)
Abstract:
An alternative cationic polymerization method is developed to produce high molecular weight polyisobutylene (HM-PIB) with molecular weights above 5 × 105 g/mol. The method involves micelle formation via functionalized low molecular weight polyisobutylene (LM-PIB) in non-polar solvent. One end of LM-PIB is modified with an imidazolium-containing ionic group, which together with the anion (e.g. Al2Cl7) works as Lewis acid. While the monomer isobutylene dissolves readily in non-polar solvent, polymerization can occur only within the micelle, which affords stable HM-PIB particles. HM-PIB with a molecular weight (MW) close to 1 × 106 g/mol was produced successfully with the described method.
Degradable Protein-loaded Polymer Capsules Fabricated by Thiol-disulfide Cross-linking Reaction at Liquid-liquid Interface
Xiaoteng Ma, Guangda Han, Hanying Zhao
Corrected proof , doi: 10.1007/s10118-019-2253-9
[Abstract](222) [FullText HTML](103) [PDF 795KB](12)
Abstract:
In these years, the encapsulation of proteins for protection and delivery purpose has attracted great interest. In this research, W/O emulsion droplets were used as soft templates and bovine serum albumin (BSA) encapsulated hollow capsules were prepared by liquid-liquid interfacial thiol-disulfide exchange reaction. Block copolymer chains with pendant pyridyl disulfide groups are located at liquid-liquid interface, and upon addition of a macromolecular crosslinking agent with multiple pendant thiol groups into an emulsion, thiol-disulfide interfacial crosslinking reactions lead to the formation of BSA encapsulated hollow capsules. The cleavage of disulfides on the membranes results in the degradation of hollow structures and the release of encapsulated protein molecules. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and confocal laser scanning microscopy were employed to characterize the hollow capsules. In comparison with native BSA, BSA molecules encapsulated in the hollow structures show higher catalytic efficiency due to higher local concentration of reactants in the structures. The membranes of the hollow capsules can efficiently protect the encapsulated BSA from hydrolysis by trypsin.
Research on the Glass Transition Temperature and Mechanical Properties of Poly(vinyl chloride)/Dioctyl Phthalate (PVC/DOP) Blends by Molecular Dynamics Simulations
Jing Li, Shao-Hua Jin, Guan-Chao Lan, Zi-Shuai Xu, Lu-Ting Wang, Na Wang, Li-Jie Li
Corrected proof , doi: 10.1007/s10118-019-2249-5
[Abstract](215) [FullText HTML](96) [PDF 624KB](22)
Abstract:
To effectively improve the performance and expand the applications of polymers, molecular dynamics (MD) simulations with the COMPASS force field have been applied to predict the miscibility, glass transition temperature (Tg), and mechanical properties of poly(vinyl chloride)/dioctyl phthalate (PVC/DOP) blends. The solubility parameter values obtained are in good agreement with the reference data and the little difference (|Δδ| < 2.0 MPa0.5) between two components indicates that PVC/DOP is a miscible system. Tg is predicted by the slope of the free volume and density versus temperature simulation data based on density and free volume theory which is agree well with the experimental data. In addition, the analyses of mechanical properties results indicate that the values of Young’s modulus (E), bulk modulus (K), and shear modulus (G) decrease with the addition of DOP, demonstrating that the rigidity of material is weakened and the ductility is improved. The mechanical properties can also be effectively improved by increasing the temperature, which may provide a more flexible mixture, with lower E, K, G but an increased ductility.
Effect of Molybdenum Disulfide Exfoliation Conditions on the Mechanical Properties of Epoxy Nanocomposites
Bin Chen, Bao-Jia Ni, Meng-Xiang Fu, Hang Zhong, Wei-Feng Jiang, Si-Yuan Liu, He-Xin Zhang, Keun-Byoung Yoon
Corrected proof , doi: 10.1007/s10118-019-2239-7
[Abstract](185) [FullText HTML](108) [PDF 725KB](17)
Abstract:
In this work, the MoS2 fillers were prepared through chemical exfoliation method and used as fillers to fabricate epoxy (EP)/MoS2 nanocomposites. The effects of molybdenum disulfide (MoS2) intercalation conditions on the properties of EP/MoS2 nanocomposites were investigated. As the intercalation time was prolonged, the surface of MoS2 exhibited a totally crumpled structure and more functional groups formed. Because of the higher functional group concentration, the interfacial adhesion force between EP and MoS2 was enhanced. With the addition of 1.0 wt% exfoliated MoS2 fillers, the tensile strength and tensile modulus of EP were even improved ~500% and ~6800%, respectively. Therefore, this work provides a facile way to produce high-performance EP nanocomposites.
Poly(1-vinylimidazole) Prospects in Gene Delivery
Elena N. Danilovtseva, Stanislav N. Zelinskiy, Viktor A. Pal'shin, Gayathri Kandasamy, Uma Maheswari Krishnan, Vadim V. Annenkov
Corrected proof , doi: 10.1007/s10118-019-2240-1
[Abstract](168) [FullText HTML](95) [PDF 1638KB](16)
Abstract:
Polymeric amines are being studied intensively as components of systems for gene delivery in genetic engineering and gene therapy of genetic disorders, including cancer. Despite remarkable achievements in the field, polymeric amines, such as polyethyleneimine, show some disadvantages. Strong interaction between the amine-containing polymer and nucleic acid hampers the release of nucleic acid in the cell cytoplasm. Amine groups can interact with the cell membrane which results in cell death. These limitations of polymeric amines stimulated an investigation of new structures for gene delivery. Imidazole-containing polymers have attracted attention as lesser basic substances, while they are able to interact with polymeric acids. Further development of imidazole-based gene delivery agents requires knowledge about some fundamental aspects of interaction between nucleic acids, and polymeric imidazoles. In this work, we studied the complexation of poly(1-vinylimidazole) and oligomeric DNA. We found that the number of active sites capable of binding with negatively charged phosphate groups is comparable with the number of protonated imidazole units in the case of high molecular weight polymer. The increase in polymer charge by 1-bromopropane quaternizating 1%−5% imidazole units or by decreasing the pH to 6.5−7 considerably increased the ability of poly(1-vinylimidazole) to interact with oligonucleotides. The pH sensitivity of this interaction is interesting for cancer gene therapy because the tumours have a lowered intercellular pH (stable oligonucleotide complex) and a higher extracellular pH which can lead to complex dissociation. Minimal critical length for complexation of quaternized poly(1-vinylimidazole) and DNA is below eight units which corresponds to polymers with amine groups. Fluorescence-tagged poly(1-vinylimidazole) samples were obtained and their potential for monitoring the polymer and polymer-oligonucleotide complex internalization into living cells was demonstrated.
Self-healing Behavior of Ethylene Propylene Diene Rubbers Based on Ionic Association
Zhi-Fei Zhang, Kun Yang, Shu-Gao Zhao, Lai-Na Guo
Corrected proof , doi: 10.1007/s10118-019-2241-0
[Abstract](141) [FullText HTML](84) [PDF 772KB](8)
Abstract:
To meet the increasing demand for safe, environmentally friendly and high-performance smart materials, self-healing rubbers are highly desired. Here, the self-healing performance of ethylene propylene diene monomer rubber (EPDM) is reported, which was designed by graft-polymerization of zinc dimethacrylate (ZDMA) onto rubber chains to form a reversible ionic cross-linked network. Single ionic cross-linked network and dual network, combining covalent and ionic cross-links, could be tuned by controlling vulcanization process to achieve tailorable mechanical and self-healing properties. It was found that ionic cross-linked EPDM showed a recovery of more than 95% of the original mechanical strength through a healing process of 1 h at 100 °C. The covalent cross-links could improve mechanical properties but block self-healing. Adding 50 wt% liquid rubber to " dry” EPDM could effectively enhance self-healing capability of the dual cross-linked network and the healed tensile strength could reach 0.9 MPa. A compromise between mechanical performance and healing capability could be potentially tailored by controlling vulcanization process and liquid rubber content.
Neodymium-catalyzed Polymerization of C5 Fraction: Efficient Synthesis of 1,3-Pentadiene-isoprene Copolymer Rubbers
Jin-Yan Hou, Fang Guo, Qian Hu, Yang Li, Zhao-Min Hou
Corrected proof , doi: 10.1007/s10118-019-2244-x
[Abstract](165) [FullText HTML](83) [PDF 766KB](9)
Abstract:
The polymerization of C5 fraction without separation and concentration by using a commercial available Nd(P204)3/AliBu3/AlEt2Cl has afforded for the first time a new kind of 1,3-pentadiene-isoprene random copolymers as rubber materials. Isoprene (IP) and E-1,3-pentadiene (EPD) acted as polymerization monomers, cyclopentadiene acted as poison, and other substances like alkanes, monoolefins, Z-1,3-pentadiene acted as solvents in this multicomponent C5 fraction polymerization system. The data of kinetic experiments, NMR, and DSC indicated that the polymerization of C5 fraction by Nd(P204)3/AliBu3/AlEt2Cl afforded the IP-EPD random copolymers. By controlling polymerization conditions such as [Al]/[Nd]/[Cl] molar ratio and polymerization temperature, the random EPD-IP copolymers containing high cis-1,4-poly(IP) (with selectivity 96%) and moderate cis-1,4-poly(EPD) (with selectivity 60%) units with a low glass transition temperature (about −60 °C), controllable molecular weight (Mn = 3.8 × 104‒14.3 × 104), and moderate molecular weight distribution (Mw/Mn = 2.17‒2.78) were obtained in a high yield.
Dispersion of Titanium(IV) Oxide Nanoparticles in Mixed Matrix Membrane Using Octaisobutyl Polyhedral Oligomeric Silsesquioxane for Enhanced CO2/CH4 Separation Performance
Grace Ying En Tan, Pei Ching Oh, Kok Keong Lau, Siew Chun Low
Corrected proof , doi: 10.1007/s10118-019-2246-8
[Abstract](173) [FullText HTML](65) [PDF 1447KB](14)
Abstract:
Titanium(IV) oxide (TiO2) nanoparticles have been incorporated into mixed matrix membranes (MMMs) to improve gas separation performance. However, TiO2 nanoparticles tend to agglomerate due to high surface energy and van der Waals forces. This leads to precipitation which causes the formation of non-homogeneous MMM morphology. In this study, the effect of octaisobutyl polyhedral oligomeric silsesquioxane (POSS) addition on TiO2/polysulfone MMM was investigated. The aims are to enhance gas separation performance whilst preventing agglomeration of TiO2 nanoparticles. The results demonstrated that inclusion of POSS as dispersant increases MMMs’ CO2/CH4 selectivity and permeance, possibly due to less void formation and more evenly distributed pore structure. For example, synergistic addition of 5 wt% TiO2 and 5 wt% POSS increased the CO2/CH4 selectivity up to 390% compared to MMM without POSS. This is supported by elemental mapping of titanium which revealed that POSS successfully dispersed TiO2 nanoparticles and prevented aggregation. TiO2-POSS/PSf MMMs also retained their favorable thermal stability.
Synthesis of Conjugated Polymers Containing Diketopyrrolopyrrole (DPP) Building Block and the Photophysical Study
Ying-Zhong Wu, Yi-Chen Zhang, Jia-Jun Chen, Li-Juan Fan
Corrected proof , doi: 10.1007/s10118-019-2248-6
[Abstract](199) [FullText HTML](88) [PDF 725KB](16)
Abstract:
Sonogashira coupling of two different diketopyrrolopyrrole (DPP)-containing dihaloarenes with the same aromatic bisalkyne resulted in two new conjugated polymers with the same backbone but different pendant groups on the DPP moiety. The polymers were found to have designed chemical structures via structural characterizations in comparison with three monomers. The molecular weight measurement further demonstrated the formation of polymers with polydispersity index around 2, consistent with the polycondensation nature of the polymerization based on Sonogashira coupling. Both polymers could dissolve in many organic solvents, and the one with long alkyl side group on DPP moiety had better solubility. Photophysical investigation showed that both polymers had typical absorption/emission of conjugated polymers, and varying the solvent did not have large influence. Compared with other polar solvents, toluene reduced the quantum yield of fluorescence of the polymers, especially for the one with long alkyl pedant group, accompanying with slight red-shift in absorption/emission. The difference in the absorption/emission wavelengths between the polymers was similar to that between the corresponding monomers. Adding water into the THF solution of polymers reduced the emission intensity but no red-shift was observed. Discussion about the structure-property relationships was carried out in detail.
Preparation of Ultralow Molecular Weight Poly(vinyl chloride) with Sub-micrometer Particles via Precipitation Polymerization
Peng Cui, Chang-Tong Song, Xian-Hong Zhang, Dong Chen, Yu-Hong Ma, Wan-Tai Yang
Corrected proof , doi: 10.1007/s10118-019-2252-x
[Abstract](172) [FullText HTML](90) [PDF 851KB](9)
Abstract:
Poly(vinyl chloride), with ultralow molecular weight, produced by free radical polymerization either at high temperature or in the presence of chain transfer agents, is widely used as special resins and polymer process additives. This paper reports a new process, called self-stabilized precipitation polymerization, in which the polymerization of vinyl chloride monomer (VCM) is conducted in hydrocarbon diluents without addition of any suspending agent or emulsifier. The merits of this novel strategy include: (1) PVC resins with ultra-low number-average molecular weight (Mn) from 4000 to 15000, which is much lower than Mn of those prepared by conventional suspension and emulsion polymerizations, (2) sub-micrometer PVC particles with near spherical morphology, and (3) the very simple post-polymerization separation process. Under mild stirring, polymerization proceeds stably and smoothly. The influences of main process factors, such as solvents, initiator and monomer concentrations, polymerization time, and temperature on both particle morphology and Mn of the polymer products are investigated systematically. The molar ratio of ―CH2―CHCl―/―CH=CH―CH2CHCl, a good indicator of structural defects, is about 1000/0.1 which means the low molecular weights do not result from chain transfer to the monomers. Then the mechanism of this polymerization is proposed. In summary, this novel polymerization technology provides a straightforward method for preparing PVC particulate products with low Mn.
Synthesis of a Rod-rod Diblock Copolymer, Poly(3-hexylthiophene)-block-poly(furfuryl isocyanate), through the Anionic Polymerization with an Oxyanionic Macroinitiator
Chang-Geun Chae, Joonkeun Min, In-Gyu Bak, Jae-Suk Lee
Corrected proof , doi: 10.1007/s10118-019-2243-y
[Abstract](163) [FullText HTML](102) [PDF 961KB](9)
Abstract:
A rod-rod diblock copolymer (diBCP), poly(3-hexylthiophene)-block-poly(furfuryl isocyanate) (P3HT-b-PFIC), was synthesized through the anionic polymerization with an oxyanionic macroinitiator of P3HT. The properties of the diBCP (molecular weight, dispersity, composition, thermal stability, UV-visible absorption, and thin film morphology) were determined by various analytical methods. P3HT-b-PFIC was blended with C60 in a toluene solution to prepare a thin film of binary electron donor/acceptor system. Such blending enabled partial conjugation of the two components by the Diels-Alder reaction between furan and C60 at 60 °C for 3 h; the mixture was then spin-cast as a thin film, and annealed at 250 °C for 24 h. Tapping-mode atomic force microscopy (AFM) revealed that P3HT and C60 domains had nanoscale interfaces without a large phase segregation. This result indicated that the microphase separation of C60-functionalized P3HT-b-PFIC preserved even at high temperature provided free C60 molecules with channels to diffuse on the sides of P3HT domain, thus preventing the macroscopic crystallization of free C60 through the interfacial stabilization.
Facile Synthesis of Functional Poly(ε-caprolactone) via Janus Polymerization
Huan Qiu, Zhe-Ning Yang, Jun Ling
Corrected proof , doi: 10.1007/s10118-019-2242-z
[Abstract](164) [FullText HTML](87) [PDF 1227KB](18)
Abstract:
Functionalized aliphatic polyesters attract increasing attentions as biocompatible and biodegradable polymers with broad applications in biological science. In this contribution, we propose a facile and controllable synthetic technique for functional poly(ε-caprolactone) (PCL) via Janus polymerization, which comprises cationic ring-opening copolymerization (ROP) of ε-caprolactone (CL) with 3,3-bis(chloromethyl) oxacyclobutane (CO) and (coordinated) anionic ROP of CL at a single propagating chain by rare earth metal triflates (RE(OTf)3) and propylene oxide, thus generating block copolymers in one step. The compositions of the copolymers of poly(CL-b-(CL-r-CO)) can be modulated by various RE(OTf)3. Scandium triflate catalyzes Janus polymerization to yield the copolymers containing the highest CO contents among all the RE(OTf)3 catalysts used with complete conversion of CL. The chlorine in CO repeating units is ready to be transferred into azide group which affords the modification sites to react with 9-ethynyl-9-fluorenol and mPEG-alkyne, respectively, via copper(I)-catalyzed azide-alkyne cycloaddition reaction with quantitative conversions of azides, as confirmed by FTIR analyses. According to NMR and SEC analyses, copolymers (PCC-g-PEG) bearing a homo-PCL block and a PEG-grafted block of poly(CO-co-CL) demonstrate well-defined chemical structures. The investigations on thermal properties reveal the strong phase separation between PCL and PEG blocks. The amphiphilic PCC-g-PEG is able to self-assemble into micelles in aqueous solution while cylindrical and lamellar morphologies are observed in bulk. We provide an efficient protocol to synthesize functional PCL combining one-step Janus polymerization and precise post-polymerization click reaction.
Evolution of Conformation and Dynamics of Solvents in Hydration Shell along the Urea-induced Unfolding of Ubiquitin
Ke-Cheng Yang, Feng-Chao Cui, Ce Shi, Wen-Duo Chen, Yun-Qi Li
Corrected proof , doi: 10.1007/s10118-019-2238-8
[Abstract](169) [FullText HTML](98) [PDF 968KB](16)
Abstract:
A clear diagram for the unfolding of protein induced by denaturant is a classical but still unsolved challenge. To explore the unfolded conformations of ubiquitin under different urea concentrations, we performed hybrid Monte Carlo-molecular dynamics simulations (MC-MD) guided by small angle X-ray scattering (SAXS) structural information. Conformational ensembles sampled by the hybrid MC-MD algorithm exhibited typical 3D structures at different urea concentrations. These typical structures suggested that ubiquitin was subjected to a sequential unfolding, where the native contacts between adjacent β-sheets at first were disrupted together with the exposure of hydrophobic core, followed by the conversion of remaining β-strands and helices into random coils. Ubiquitin in 8 mol·L−1 urea is almost a random coil. With the disruption of native structure, urea molecules are enriched at protein hydrated layer to stabilize newly exposed residues. Compared with water, urea molecules prefer to form hydrogen bonds with the backbone of ubiquitin, thus occupying nodes of the hydrogen bonding network that construct the secondary structure of proteins. Meanwhile, we also found that the slow dynamics of urea molecules was almost unchanged while the dynamics of water was accelerated in the hydration shell when more residues were unfolded and exposed. The former was also responsible for the stabilization of unfolded structures.
Diffusion Mode Transition between Gaussian and Non-Gaussian of Nanoparticles in Polymer Solutions
Yi Ye, Han Qin, Ming Tian, Jian-Guo Mi
Corrected proof , doi: 10.1007/s10118-019-2237-9
[Abstract](168) [FullText HTML](87) [PDF 1204KB](3)
Abstract:
The dynamic density functional theory is applied to study the diffusion of nanoparticles in polymer solutions, in which different diffusion modes have been identified by exploiting the density and free energy evolutions. Under the condition of low polymer concentration, diffusion is controlled by particle free motion with a normal Gaussian type. As the concentration increases, the non-Gaussian behavior can be observed when the particle size is comparable to the correlation length of polymer chain. Particles need to penetrate through a cage and overcome an entropic barrier, where the hopping and the model-coupling diffusion coexist. Further increase of polymer concentration can result in complete restriction of the particle by surrounding polymer segments. In this case, the non-Gaussian process fades away, and particle diffusion is controlled by Rouse dynamics of polymer chains with the generalized Gaussian characteristics.
Direct Comparison of Crystal Nucleation Activity of PCL on Patterned Substrates
Jian Hu, Rui Xin, Chun-Yue Hou, Shou-Ke Yan, Ji-Chun Liu
Corrected proof , doi: 10.1007/s10118-019-2226-z
[Abstract](178) [FullText HTML](81) [PDF 1017KB](12)
Abstract:
A sample containing different regions with poly(ε-caprolactone) (PCL), oriented polyethylene (PE), and oriented isotactic polypropylene (iPP) films in contact with glass slide has been prepared to be observed in the same view field in an optical microscope and the crystallization of PCL in different regions during cooling from 80 °C down to room temperature at a rate of 1 °C·min−1 was studied. The results showed that the crystallization of PCL started first at the PE surface and then at the iPP surface, while its bulk crystallization occured much later. This indicates that though both PE and iPP are active in nucleating PCL, the nucleation ability of PE is stronger than that of iPP. This was due to a better lattice matching between PCL and PE than that between PCL and iPP. Moreover, since lattice matching existed between every (hk0) lattice planes of both PCL and PE but only between the (100)PCL and (010)iPP lattice planes, the uniaxial orientation feature of the used PE and iPP films resulted in the existence of much more active nucleation sites of PCL on PE than on iPP. This led to the fact that the nucleation density of PCL at PE surface was so high that the crystallization of PCL at PE surface took place in a way like the film developing process with PCL microcrystallites happened everywhere with crystallization proceeding simultaneously. On the other hand, even though iPP also enhanced the nucleation density of PCL evidently, the crystallization of PCL at iPP surface included still a nucleation and crystal growth processes similar to that of its bulk crystallization.
The Influence of Trans-1,4-poly(butadiene-co-isoprene) Copolymer Rubbers (TBIR) with Different Molecular Weights on the NR/TBIR Blends
Hao Wang, Ri-Guo Wang, Yun-Sheng Ma, Bo Luan, Ai-Hua He
Corrected proof , doi: 10.1007/s10118-019-2229-9
[Abstract](144) [FullText HTML](74) [PDF 866KB](7)
Abstract:
The molecular weight of a polymer is of prime importance and greatly influences the processing and mechanical properties of the polymer. Trans-1,4-poly(butadiene-co-isoprene) multi-block copolymer rubbers (TBIR) exhibit outstanding fatigue resistance, low heat build-up and good abrasion resistance, and are expected to be desirable candidate for high performance tire. Study on the influence of TBIR with different molecular weights on the structure and properties of TBIR and natural rubber (NR)/TBIR blends is essential to understand its contribution to the greatly improved dynamic properties of the rubber vulcanizates. TBIR with different molecular weights characterized by 1H-NMR, 13C-NMR, GPC, and DSC were highly trans-1,4-copolymers with similar chain sequence distribution and crystalline trans-1,4-polyisoprene (TPI) blocks. The green strength and modulus of TBIR increased with the increasing molecular weight. The NR/TBIR compounds filled with 40 phr carbon black were chemically cured by sulfur for the preparation of NR/TBIR vulcanizates. The compatibility between NR and TBIR, filler distribution, crosslinking bond and density, and properties of NR/TBIR vulcanizates were studied. The NR/TBIR vulcanizates showed increasing tensile strength, hardness, modulus, rebound, abrasion resistance, and flexural fatigue properties with increasing molecular weight of TBIR. Furthermore, they presented significant improvement in flexural fatigue resistance when compared with that of NR vulcanizate. The contribution mechanism of TBIR on the NR/TBIR blends was discussed. The TBIR with a wide range of molecular weight are ideal rubbers for high performance tires.
A Phenol-containing α-Diimine Ligand for Nickel- and Palladium-Catalyzed Ethylene Polymerization
Chen Tan, Wen-Min Pang, Chang-Le Chen
Corrected proof , doi: 10.1007/s10118-019-2232-1
[Abstract](257) [FullText HTML](86) [PDF 936KB](52)
Abstract:
A phenol-containing dibenzhydryl-based α-diimine ligand bearing hydroxy group on para-position of aniline moiety was designed, synthesized, and investigated in Ni- and Pd-catalyzed ethylene polymerization. The Ni complex bearing hydroxy groups resulted in not only high polyethylene molecular weight (Mn up to 1.5 × 106), but also significantly increased melting temperature (Tm up to 123 °C) and greatly decreased branching density (33/1000C) versus the Ni catalyst bearing OMe group on para-position of aniline moiety. This is consistent with the hypothesis that the deprotonation of the phenol moiety generated a phenoxide bearing strong electron-donating O substituent by methylaluminoxane (MAO) cocatalyst. The Pd complexes bearing hydroxy groups exhibited similar catalytic properties to those of the Pd catalyst bearing OMe groups did.
Regioselective Polymerizations of α-Olefins with an α-Diamine Nickel Catalyst
Heng Liao, Jie Gao, Liu Zhong, Hai-Yang Gao, Qing Wu
Corrected proof , doi: 10.1007/s10118-019-2227-y
[Abstract](221) [FullText HTML](98) [PDF 717KB](17)
Abstract:
Polymerizations of linear α-olefins (CnH2n, CH2=CH―R, R = Cn−2) catalyzed by early transition metals typically afford amorphous polymers with alkyl chains (Cn−2), while chain-straightening polymerizations of α-olefins with nickel-based catalysts produce semicrystalline polyolefins. Polymerizations of various α-olefins were carried out using an α-diamine nickel catalyst with a significantly distorted chelating ring. The influences of temperature, monomer concentration, and chain length of α-olefins on polyolefin microstructure were examined in detail. The α-diamine nickel catalyst realized highly regioselective 2,1-insertion of α-olefins regardless of reaction temperature and monomer concentration. Increased chain length of α-olefins led to the formation of more linear polyolefin. Semicrystalline polyolefins with high melting temperatures (Tm) were made from α-olefins through highly regioselective 2,1-insertion and precise chain-straightening.
Synthesis of Alkyne-functionalized Polymers via Living Anionic Polymerization and Investigation of Features during the Post-“thiol-yne” Click Reaction
Lin-Can Yang, Li Han, Hong-Wei Ma, Pi-Bo Liu, He-Yu Shen, Chao Li, Song-Bo Zhang, Yang Li
Corrected proof , doi: 10.1007/s10118-019-2203-6
[Abstract](406) [FullText HTML](96) [PDF 6630KB](23)
Abstract:
" Thiol-yne” click reaction has already been widely applied in synthesis and modification of new polymer structures or novel materials due to its specific features. However, in most studies, only chain-end strategy was employed when using the di-addition feature of thiol-yne reaction, thus the in-chain di-addition strategy could endow us with a broader space to develop the synthesis of advanced polymers. Therefore, in this paper, the features of in-chain mono- and di-addition were investigated when modifying the alkyne-functionalized polymers to prepare grafted polymers via thiol-yne click reaction. The results showed that it is almost impossible to obtain the in-chain di-adducts even under excess feeding of chain-end thiol-functionalized grafts, while only the in-chain mono-adducts could be obtained efficiently. Further researches investigated that the controlled grafting could be encountered when carrying out the thiol-yne click reaction between chain-end alkyne-functionalized polystyrenes and chain-end thiol-functionalized polystyrenes under proper feedings. Therefore, the effect of steric-hindrance might be the primary reason for the alternative grafting via thiol-yne click reaction between in-chain and chain-end alkyne-functionalized polymers.
A User-friendly Living Cationic Polymerization: Degenerative Chain-transfer Polymerization of Vinyl Ethers by Simply Using Mixtures of Weak and Superstrong Protonic Acids
Mineto Uchiyama, Masataka Sakaguchi, Kotaro Satoh, Masami Kamigaito
Corrected proof , doi: 10.1007/s10118-019-2233-0
[Abstract](143) [FullText HTML](71) [PDF 729KB](3)
Abstract:
Mixtures of a weak protonic acid and a trace amount of superstrong protonic acid were used for the simple control of the cationic polymerization of vinyl ethers via a degenerative chain-transfer mechanism, in which the former acid works as a precursor of the chain transfer agent (CTA) or the dormant species and the latter works as a source of the cationic propagating species. The addition of mixtures of phosphoric acid dibutyl ester ((n-BuO)2PO2H) or 1-octanethiol (n-C8H17SH) and a trace amount of trifluoromethanesulfonic acid (TfOH) to a solution of isobutyl vinyl ether (IBVE) at −78 °C resulted in polymers with controlled molecular weights, which were basically determined by the feed ratio of IBVE to the weak protonic acid, and narrow molecular weight distributions (Mw/Mn ≈ 1.1). These results were almost the same as those obtained using their prepared adducts of IBVE as CTAs in the presence of a trace amount of TfOH under similar conditions. Methanesulfonic acid (CH3SO3H), whose adduct of IBVE has not been isolated due to instability, was similarly used in conjunction with trace TfOH to result in controlled molecular weights but slightly broader MWDs (Mw/Mn = 1.2–1.8). These results indicate that the sulfoxonium ion is also an effective intermediate in the cationic DT polymerization in addition to the phosphonium and sulfonium intermediates derived from (n-BuO)2PO2H and n-C8H17SH, respectively. The simple living cationic polymerization was thus achieved by using a combination of a weak protonic acid and a trace amount of TfOH, which are both easily available, low cost, free from metal, and easy to handle, without need for preparation of the initiator.
Copolymerization of Azobenzene Bearing Monomer and 3,4-Ethylene Dioxythiophene (EDOT): Improved Electrochemical Performance for Electrochromic Device Applications
Serife O. Hacioglu
Accepted Manuscript , doi: 10.1007/s10118-019-2306-0
[Abstract](42) [PDF 2466KB](6)
Abstract:
In this study, novel electrochromic copolymers of 3,4-ethylenedioxythiophene (EDOT) and (E)-1,2-bis(2-fluoro-4-(4-hexylthiophen-2-yl)phenyl)diazene (M1) with different monomer feed ratios were designed and synthesized via electrochemically. Electrochemical and spectroelectrochemical characterizations were performed by using voltammetry and UV-Vis-NIR spectrophotometer techniques to test the applicability of copolymers for electrochromic applications. In terms of electrochemical behaviors, addition of an electron rich EDOT unit into the azobenzene comprising copolymer increased the electron density on the polymer chain and resulting copolymers with very low oxidation potentials at around 0.30 V. While the homopolymers (P1 and PEDOT) exhibited neutral state absorptions centered at 510 nm and 583 nm, EDOT bearing copolymers showed red shifted absorptions compared to those of P1 with lower optical band gaps. In addition, the poor optical contrast and switching times of azobenzene bearing homopolymer were significantly improved with EDOT addition into the copolymer chain. As a result of promising electrochromic and kinetic preperties, CoP1.5 bearing single layer electrochromic device which works between purple and light greenish blue colors were constructed and characterized.
Phase behaviors of soft-core particle systems
Ning Xu
Accepted Manuscript , doi: 10.1007/s10118-019-2304-2
[Abstract](30) [PDF 4733KB](1)
Abstract:
This paper reviews some of our recent work on phase behaviors of particulate systems with a soft-core interaction potential. The potential is purely repulsive and bounded, i.e., it is nite even when two particles completely overlap. The one-sided linear spring (harmonic) potential is one of the representatives. This model system has been successively employed to study the jamming transition, i.e., the formation of rigid and disordered packings of hard particles, and establish the jamming physics. This actually takes advantage of the hard" aspect of the potential, because at low densities and when particle overlap is tiny the potential resembles the hard sphere limit. At high densities, the potential exhibits its soft" aspect: With the increase of density, there are successive reentrant crystallizations with many types of solid phases. Taking advantage of the dual nature of the potential, we investigate the criticality of the jamming transition from di erent perspectives, extend the jamming scenario to high densities, reveal the novel density evolution of two-dimensional melting, and nd unexpected formation of quasicrystals. It is surprising that such a simple potential can exhibit so rich and unexpected phenomena in phase transitions. The phase behaviors discussed in this paper are also highly regarded in polymer science, which may thus shed light on our understanding of polymeric systems or inspire new ideas in studies of polymers.
Recent Progress on COS-Derived Polymers
Cheng-Jian Zhang, Xing-Hong Zhang
Accepted Manuscript , doi: 10.1007/s10118-019-2288-y
[Abstract](73) [PDF 855KB](4)
Abstract:
The synthesis of sulfur-containing polymer, a very promising functional material, has made a great progress in recent years. This review is focused on the very recent advances in poly(monothiocarbonate)s derived from carbonyl sulfide (COS) and epoxides including biomass-derived epoxides. Of significance, metal-free catalyst systems, triethyl borane/Lewis base pair and thiourea/Lewis base pair, are developed for the alternating copolymerization of COS with epoxides. Thereof, the thiourea/Lewis base pair is highly active to the copolymerization of COS with epoxide in a living manner. Moreover, a series of crystalline poly(monothiocarbonate)s are presented, including the copolymers derived from COS with oxetane, ethylene oxide, enantiopure epichlorohydrin, and achiral meso-epoxides via enantioselective copolymerization. Based on these COS/epoxide copolymerization process, a variety of COS-based block copolymers with well-defined structure are presented.
Effect of Butyl α Hydroxymethyl Acrylate Monomer Structure on the Morphology Produced via Aqueous Emulsion Polymerization-Induced Self-Assembly
Shou-kuo Man, Xiao Wang, Jin-wen Zheng, and Ze-sheng An
Accepted Manuscript , doi: 10.1007/s10118-019-2303-3
[Abstract](38) [PDF 1968KB](5)
Abstract:
Polymerization-induced self-assembly (PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast majority of emulsion PISA formulations using insoluble monomers leads to kinetically-trapped spheres. Herein, we present aqueous emulsion PISA formulations generating worms and vesicles besides spheres. Two monomers with different butyl groups, n-butyl (nBHMA) and tert-butyl (tBHMA) α-hydroxymethyl acrylate, and thus different water solubility were synthesized via Baylis-Hillman reaction. Photoinitiated aqueous emulsion polymerizations of nBHMA and tBHMA employing poly(ethylene glycol) macromolecular chain transfer agents (macro-CTAs, PEG45-CTA and PEG113-CTA) at 40 °C were systematically investigated to evaluate the effect of monomer structure and solubility on the morphology of the generated block copolymer nano-objects. Higher order morphologies including worms and vesicles were readily accessed for tBHMA, which has a higher water solubility than nBHMA. This study proves that plasticization of the core-forming block by water plays a key role in enhancing chain mobility required for morphological transition in emulsion PISA.
Photo-grafting Poly(acrylic acid) onto Poly(lactic acid) Chains in Solution
Jiaxing Wang, Yanbin Huang, and Wantai Yang
Accepted Manuscript , doi: 10.1007/s10118-019-2308-y
[Abstract](31) [PDF 1427KB](5)
Abstract:
Poly(lactic acid) (PLA) is one of the most important bio-plastics, and chemical modification of already-polymerized poly(lactic acid) chains may enable optimization of its material properties and expand its application areas. In this study, we demonstrated that poly(lactic acid) can be readily dissolved in acrylic acid at room temperature, and acrylic acid can be graft polymerized onto poly(lactic acid) chains in solution with the help of photoinitiator benzophenone under 254 nm ultraviolet (UV) irradiation. Similar photo-grafting polymerization of acrylic acid (PAA) had only been studied before in the surface modification of polymer films. The graft ratio can be controlled by various reaction parameters, including irradiation time, benzophenone content, and monomer/polymer ratios. This photo-grafting reaction resulted in high graft ratio (graft ratio PAA/PLA up to 180%) without formation of homopolymers of acrylic acid. When the PAA/PLA graft ratio was higher than 100%, the resulted PLA-g-PAA polymer was found dispersible in water.The pros and cons of the photo-grafting reaction were also discussed.
Orientation Efforts as Regulatory Factor of Structure Formation in Permeable Porous Polyvinylidene fluoride Films
G.K. Elyashevich, I.S. Kuryndin, I.Yu. Dmitriev, V.K. Lavrentyev, N.N. Saprykina, V. Bukošek
Accepted Manuscript , doi: 10.1007/s10118-019-2284-2
[Abstract](66) [PDF 421KB](4)
Abstract:
The manufacturing process of polyvinilidenfluoride microporous films containing through flow channels and permeable to liquids has been elaborated. The process is based on polymer melt extrusion with subsequent stages of annealing, uniaxial extensions (“cold” and “hot” drawing) and thermal stabilization. The effect of orientation parameters (melt draw ratio and extension degrees) on overall porosity, permeability, morphology and content of polar piezoactive β-phase in crystalline structure of the films is investigated by filtration porosimetry, sorptometry, scanning electron microscopy, X-ray scattering and mechanical properties measurements. It is shown that the through pores are formed by a percolation mechanism. It is observed that permeability and the β-phase content increase with the growth of extension degree at the pore formation stages but the portion of β-crystallites decreases with increasing of melt draw ratio at extrusion that permits to regulate the combination of through permeability and piezoactivity values by variation of the preparation process parameters.
Competition between liquid-liquid demixing, crystallization and glass transition in solutions of PLA of different stereochemistry and DEET
Chanita Sungkapreecha, Walter W. Focke, and René Androsch
Accepted Manuscript , doi: 10.1007/s10118-019-2314-0
[Abstract](9) [PDF 801KB](3)
Abstract:
Liquid-liquid (L-L) de-mixing and vitrification of solutions of either crystallizable poly (L-lactic acid) (PLLA) or non-crystallizable poly (D/L-lactic acid) (PDLLA) with 50 m-% N, N-diethyl-3-methylbenzamide (DEET) were analyzed by calorimetry and cloud-point measurements, allowing drawing conclusions about the effect of the polymer stereochemistry on the phase behavior. Regardless of the PLA stereochemistry, vitrification of the solutions on fast cooling, hindering crystallization of PLLA, occurred below -20 °C and suppressed prior L-L de-mixing. The experimental results prove that crystallization in samples containing crystallizable PLLA, observed at around 55 °C on slow cooling, is not preceded by L-L de-mixing.
Rhodamine Mechanophore Functionalized Mechanochromic Double Network Hydrogels with High Sensitivity to Stress
Li-Jun Wang, Kai-Xiang Yang, Qiang Zhou, Hai-Yang Yang, Jia-Qing He, and Xing-Yuan Zhang
Accepted Manuscript , doi: 10.1007/s10118-019-2293-1
[Abstract](73) [PDF 1414KB](9)
Abstract:
Mechanochromic hydrogels, a new class of stimuli-responsive soft materials, have potential applications in a number of fields such as damage reporting and stress/strain sensing. We prepared a novel mechanochromic hydrogel using a strategy that has been developed to prepare dual-network (DN) hydrogels. A hydrophobic rhodamine derivative (Rh mechanophore) was covalently incorporated into a first network as a cross-linker. This first network embedded with Rh mechanophore within the DN hydrogel was pre-stretched. This guaranteed that the stress could be transferred extensively to the Rh- rosslinked first network once the hydrogel was under an applied force. Interestingly, we found that the threshold stress required to activate the mechanochromism of the hydrogel was less than 200 kPa, and much less than in previous reports. Moreover, because of the excellent sensitivity of the hydrogel to stress, the DN hydrogel exhibited reversible freezing-induced mechanochromism. Benefiting from the sensitivity of Rh mechanophore to both pH and force, the DN hydrogel showed pH-regulated mechanochromic behavior. Our experimental results indicate that the preparation strategy we used introduces sensitive mechanochromism into the hydrogel and preserves the advantageous mechanical properties of the DN hydrogel. These results will be beneficial for the design and preparation of mechanochromic hydrogels with high stress sensitivity, and foster their practical applications in a number of fields such as damage reporting and stress/strain sensing.
Enhanced Mechanical Properties of Poly(arylene sulfide sulfone) Membrane by co-Electrospinning with Poly(m-xylene adipamide)
Lu Chen, Xinlin Tuo, Xichuan Fan, Chunjie Xie, Bao-Hua Guo, Jian Yu, Ping Hu, and Zhao-Xia Guo
Accepted Manuscript , doi: 10.1007/s10118-019-2297-x
[Abstract](46) [PDF 1332KB](2)
Abstract:
The mechanical properties of poly(arylene sulfide sulfone) (PASS) electrospun membrane were significantly enhanced by co-electrospinning with semi-aromatic nylon poly(m-xylene adipamide) (MXD6), another engineering plastic with high thermal stability and good mechanical properties. The tensile strength of PASS membrane increased with increased incorporation of MXD6, and was tripled when 20% MXD6 was incorporated. The mechanism of the mechanical property improvement is the existence of hydrogen bonding interaction between PASS and MXD6 and between adjacent fibers at the intersections. The thermal properties of the PASS/MXD6 membranes were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), showing that the membranes can be stably utilized up to 180 ℃ without any change in appearance and without decomposition. The contact angle measurements of all the membranes showed hydrophobic character. To demonstrate the potential applications of PASS/MXD6 blend membranes, their oil absorption capacities were evaluated with three oils of different viscosities, proving that the PASS/MXD6 membranes are better absorbents than commercial non-woven polypropylene fibers. Therefore, PASS/MXD6 fibrous membranes produced by electrospinning have a great potential in practical applications.
Phthalonitrile Resins Derived from Vanillin: Synthesis, Curing Behavior and Thermal Properties
Yue Han, Dong-Hao Tang, Guang-Xing Wang, Ya-Nan Sun, Ying Guo, Heng Zhou, Wen-Feng Qiu, and Tong Zhao
Accepted Manuscript , doi: 10.1007/s10118-019-2311-3
[Abstract](24) [PDF 1597KB](3)
Abstract:
Vanillin was used as sustainable source for phthalonitrile monomer synthesis, and allyl/propargyl ether moieties were introduced to improve the processability at the minimal cost of thermal properties. The synthesis route was optimized to minimize side-reactions and simplify post-processing, and the monomers were obtained in high purities and good yields. The curing behavior, mechanism and processability of the monomers were studied, and the thermal properties of cured polymers were evaluated. Of the two monomers, the allyl ether containing one exhibited a wide processing window of 185 oC, and was mainly cured into phthalocyanine and linear aliphatic structures through self-catalytic curing process. Also the glass transition temperature was higher than 500 oC. On the contrary, the propargyl ether containing monomer could be only partially cured, and compromise in heat resistance was found. Compared with traditional petroleum-based phthalonitrile resins, the bio-based monomers could be cured without addition of catalysts, and improvement in processability was achieved at no cost of thermal performances.
A Well-defined Hierarchical Hydrogen Bonding Strategy to Polyureas with Simultaneously Improved Strength and Toughness
Ting Li, Tianze Zheng, Zhao-Xia Guo, Jun Xu, and Bao-Hua Guo
Accepted Manuscript , doi: 10.1007/s10118-019-2275-3
[Abstract](69) [PDF 5445KB](1)
Abstract:
A well-defined quadruple hydrogen bonding strategy involving dimerization of 2-ureido-4[1H]-pyrimidone (UPy) units is innovatively designed to prepare polyureas with high overall mechanical properties. Three polyureas containing different amounts of UPy units were synthesized by replacing a portion of isophorone diisocyanate (IPDI) with a UPy-derived diisocyanate. The formation of quadruple hydrogen bonds in hard segments via UPy dimers were confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the polyureas were evaluated by uniaxial tensile testing. Compared to the polyurea without UPy units, remarkable improvements in Young’s modulus, tensile strength and toughness were simultaneously achieved when UPy units were incorporated. The mechanism behind the strong strengthening effect was attributed to the stronger intermolecular forces among hard segments brought by the quadruple hydrogen bonds, which is stronger than the inherent bidentate and monodentate hydrogen bonds among urea groups, and the slower soft segmental dynamics reaveled by both increased Tg and relaxation time of the soft segments. The mechanism behind the strong toughening effect was ascribed to more effective energy dissipation brought by the quadruple hydrogen bonds serving as stronger sacrificial bonds upon deformation. This work may offer new insight into the design of polyurea elastomers with comprehensively improved mechanical properties.
Simulation Study on the Extension of Semi-flexible Polymer Chains in Cylindrical Channel
Yu Fu, Fan Wu, Jian-Hua Huang, Ying-Cai Chen, Meng-Bo Luo
Accepted Manuscript , doi: 10.1007/s10118-019-2291-3
[Abstract](69) [PDF 741KB](6)
Abstract:
The scaling relations among the mean end-to-end distance of polymer along the channel , the polymer length N, and the effective diameter of channel De, were investigated for flexible and semi-flexible polymer chains confined in long cylindrical channels. For the flexible polymer chain, scaling relation ~ NDe0.7 was found in the classic de Gennes regime at lp2/b < De < Rg with lp the persistence length, b the bond length and Rg the radius of gyration of polymer. For the semi-flexible polymer, ~ NDe1 in the transition regime lp < De < xlp (x > 1) and ~ De0.7 in the classic de Gennes regime at larger De > xlp were observed. The simulation results revealed that the scaling relation in the transition regime was due to the rod-like behavior of the semi-flexible polymer in the small regime lp < De < xlp.
A Luminescent Thermometer Based on Linearly Thermo-Responsive Copolymer and Polyoxometalates
Jinlong Zhang, Junyan Tan, Xinhua Wan, Jie Zhang
Accepted Manuscript , doi: 10.1007/s10118-019-2287-z
[Abstract](70) [PDF 950KB](4)
Abstract:
A novel switchable luminescent thermometer based on thermo-responsive triblock copolymer poly (ethyleneglycol)-b-poly(acrylamide-co-acrylonitrile-co-dimethylaminoethylmethacrylate)(PEO113-b-P(AAm264-co-AN112-co-DMA8)) and Eu-containing polyoxometalate (Eu-POM) was successfully constructed. The copolymer synthesized by RAFT exhibits a linear response to temperature variations in aqueous media, which is quite different from the uncharged copolymer P(AAm-co-AN) having a specific upper critical solution temperature (UCST). Eu-POM was surrounded around thermo-responsive blocks through electrostatic interactions, and its luminescence could be finely tuned due to the sensitivity of copolymer to the temperature variation. In the cold water, POMs was trapped in highly hydrophobic cores, exhibiting an intense emission. With the upraising of temperature, the emission intensity presents a gradual decrease and shows a linear correlation with temperature. When the complex solution cooled down, the luminescence could also be perfectly restored. This temperature-luminescence correlation could be held for numerous trials, showing a potential application in thermometer.
Monomer-activated copolymerization of Ethylene Oxide and Epichlorohydrin: In Situ Kinetics Evidences Tapered Block Copolymer Formation
Ann-Kathrin Danner, Daniel Leibig, Lea-Marie Vogt, and Holger Frey
Accepted Manuscript , doi: 10.1007/s10118-019-2296-y
[Abstract](52) [PDF 1304KB](1)
Abstract:
The monomer-activated anionic ring-opening copolymerization (AROP) of ethylene oxide (EO) and epichlorohydrin (ECH) using tetraoctylammonium bromide as an initiator and triisobutylaluminum (i-Bu3Al) as an activator was studied. The properties of the copolymers as well as the microstructure have been analyzed in detail via an in situ NMR kinetics study. The statistical copolymers exhibit molecular weights ranging from 2,350 to 38,000 g·mol-1 (measured by SEC, PEG-standards) and moderate dispersities of 1.27-1.44. The thermal properties reveal both a glass transition and melting for all copolymers, supporting a block-like nature. Applying in situ NMR kinetic measurements, the reactivity ratios of EO and ECH were determined to be strongly disparate, i.e., rEO = 9.2 and rECH = 0.10. This shows that the simple one-pot statistical anionic copolymerization of EO and ECH via the monomer-activated AROP results in the formation of strongly tapered, block like structures. Furthermore, post-polymerization functionalization of the reactive chloromethyl groups by nucleophilic displacement was investigated at the copolymers. Copolymerization of EO and ECH offers a broad platform for further functionalization and therefore the possibility to prepare a variety of multifunctional PEGs.
Facile Synthesis of Functional Poly(methyltriazolylcarboxylate)s by Solvent- and Catalyst-Free Butynoate-Azide Polycycloaddition
Weiwen Chi, Rongyuan Zhang, Ting Han, Jian Du, Hongkun Li, Weijie Zhang, Yongfang Li, and Ben Zhong Tang
Accepted Manuscript , doi: 10.1007/s10118-019-2316-y
[Abstract](5) [PDF 1082KB](14)
Abstract:
The copper-catalyzed and metal-free azide–alkyne click polymerizations have become efficient tools for polymer synthesis. However, the 1,3-dipolar polycycloadditions between internal alkynes and azides are rarely employed to construct functional polymers. Herein, the polycycloadditions of dibutynoate (1) and tetraphenylethene-containing diazides (2) are carried out at 100 oC for 12 h under solvent- and catalyst-free conditions, producing soluble poly(methyltriazolylcarboxylate)s (PMTCs) with high molecular weights in high yields. The resultant polymers are thermally stable with 5% weight loss emperatures up to 377 oC. The PMTCs show aggregation-induced emission (AIE) properties. They can work as fluorescent sensors for detecting explosive with high sensitivity, and generate two-dimensional fluorescent photopatterns with high resolution. Furthermore, their triazolium salts can be utilized for cell-imaging applications.
Cationic polymerization of isobutylene and C4 mixed feed using complexes of Lewis acids with ethers: a comparative study
Dmitriy I. Shiman, Ivan A. Berezianko, Irina V. Vasilenko, Sergei V. Kostjuk
Accepted Manuscript , doi: 10.1007/s10118-019-2290-4
[Abstract](66) [PDF 546KB](4)
Abstract:
The cationic polymerization of C4 mixed feed and isobutylene co-initiated by AlCl3OiPr2, iBuAlCl2nOiPr2 and emimCl-FeCl3nOiPr2 (emimCl: 1-ethyl-3-methylimidazolium chloride) has been investigated. AlCl3OiPr2 co-initiated cationic polymerization of C4 mixed feed proceeds at a lower rate than polymerization of isobutylene affording polymers with higher molecular weight. Complexes of iBuAlCl2 with diisopropyl ether of different composition are more suitable co-initiators than AlCl3OiPr2 for the synthesis of HR PIB from C4 mixed feed due to their higher activity in the polymerization as well as possibility to prepare polyisobutylenes with lower molecular weight and higher content of exo-olefin end groups. However, iBuAlCl2 requires the activation via addition of external water (initiator) and/or interaction with salts hydrates in order to increase the reaction rate and the saturated monomer conversion. EmimCl-FeCl3/iPr2O is quite promising catalyst for the preparation of HR PIB with high exo-olefin end group content (>80%) and relatively low polydispersity (Mw/Mn<2.8) via cationic polymerization of C4 mixed feed. The sonication of reaction mixture in case of using emimCl-FeCl3 allowed increasing the reaction rate and decreasing the molecular weight.
Investigation on Viscoelasticity of Waterborne Polyurethane with Azobenzene-Containing Pendant Groups under Ultraviolet and Visible-Light Irradiation
Yijun Liu, Dong Liu, Sihan Li, Huaqing Liang, and Fangming Zhu
Accepted Manuscript , doi: 10.1007/s10118-019-2289-x
[Abstract](78) [PDF 2394KB](10)
Abstract:
In this study, a novel waterborne polyurethane (WPU) with azobenzene-containing (azo-containing) pendant groups was synthesized by isophorone diisocyanate, long-chain diol of polycaprolactone, 2-ethyl-2-methyl-butanoic acid (2, 2-dimethylolpropionic acid), 10-(4- (phenyldiazenyl)phenoxy) decyl-3-hydroxy-2- (hydroxymethyl)-2-methylpropanoate and N, N-diethyl-ethanamine (triethylamine). Moreover, the influence of ultraviolet and visible (UV-Vis) light irradiation on the viscoelasticity of azo-containing WPU film in terms of the reversible trans-cis photoisomerization of azo-containing pendant groups was investigated by UV-Vis light spectrum, atomic force microscope and dynamic thermomechanical analyzer. The results revealed that the adhesion of azo-containing WPU with single crystal silicon atomic force microscope probe was about 13 nN irradiated by 450 nm Vis light for 60 s at 25 ºC. Subsequently, the adhesion increased to 82 nN after irradiation with 365 nm UV light for 60 s at 25 ºC. In addition, the azo-containing WPU presented a photo-induced reversible transition of tensile modulus and tan δ in the range from about 2 to 22 MPa and 6000 to 0.35 with UV-Vis light cyclic irradiation for 120 s at 25 ºC, respectively.
Direct-Writing Structure Color Patterns on the Electrospun Colloidal Fibers toward Wearable Materials
Shujian Yuan, Weihao Meng, Aihua Du, Xinyu Cao, Yong Zhao, Jingxia Wang and Lei Jiang
Accepted Manuscript , doi: 10.1007/s10118-019-2286-0
[Abstract](89) [PDF 2437KB](0)
Abstract:
This paper presents a direct-writing structure color patterns on electrospun colloidal fibers by inkjet printing. The colloidal fiber was obtained by electrospinning the aqueous mixture of colloidal particles of poly(styrene-methyl methacrylate-acrylic acid) and polyvinyl alcohol. The pattern was obtained by directly inkjet printing water onto the electrospun colloidal fiber. The pattern formation is attributed to the morphological transition of the colloidal fiber from the fiber aggregation to latex aggregation and the corresponding color change owing to the dissolution of polyvinyl alcohol by water. Interestingly, a clear and clean image was successfully obtained onto ethanol-treated colloidal fibers film, comparing a confused and blur image onto the fresh-made film. It is because that the treatment process can compact the fiber structure, lower the spreading/wetting behavior of the ink on the fiber structure, contributing to the formation of high-quality pattern. Various letters or two-dimensional code, were flexibly designed and printed on colloidal fibers. Furthermore, the pattern can be easily transferred onto flexible substrate, i.e., a flexible printed bracelet. This work will be of great significance for the development of novel wearable function materials/devices based on electrospun colloidal fiberes.
Polypropylene Separators with Robust Mussel-Inspired Coatings for High Lithium-Ion Battery Performances
Chao Zhang, Hong-Qing Liang, Jun-Ke Pi, Guang-Peng Wu, and Zhi-Kang Xu
Accepted Manuscript , doi: 10.1007/s10118-019-2310-4
[Abstract](11) [PDF 2660KB](2)
Abstract:
The performances of lithium-ion batteries (LIBs) are dependent on the wettability and stability of porous separators. Mussel-inspired coatings seem to be useful to improve the surface wettability of commercialized polyolefin separators. However, it is still a challenge to guarantee their stability under polar electrolytes. Herein, we report a facile and versatile way to enhance the wettability and stability of polypropylene separators by constructing robust polydopamine (PDA) coatings triggered with CuSO4/H2O2. These coatings are conveniently deposited on the polypropylene separator surfaces and the PDA-coated separators exhibit improved surface wettability and thermal stability. The electrolyte uptake increases nearly two fold from the pristine separator to the modified ones. Correspondingly, the ionic conductivity also rises from 0.82 mScm-1 to 1.30 mScm-1. Most importantly, the CuSO4/H2O2-triggered PDA coatings are very stable under strong polar electrolytes, endowing the cells with excellent cycle performance and enhanced C-rate capacity. Overall, the results unequivocally demonstrate that application of PDA coatings on polyolefin separator triggered by CuSO4/H2O2 is a facile and efficient method to improve the wettability and stability of separators for high LIBs performance.
Dendronized polymers with high FTC-chromophore loading density: large second-order nonlinear optical effects, good temporal and thermal stability
Meng Jin, Zhaochen Zhu, Qiuyan Liao, Qianqian Li, and Zhen Li
Accepted Manuscript , doi: 10.1007/s10118-019-2307-z
[Abstract](46) [PDF 659KB](9)
Abstract:
In this paper, two new dendronized nonlinear optical (NLO) polymers were synthesized with high FTC chromophore loading density by the introduction of high generation chromophore dendrons on the side chains. Due to their suitable molecular weights, both of them possess good solubility in common solvents. They also inherited the advantages of dendrimers (large NLO coefficient), especially for PG2, its NLO coefficient d33 value was as high as 282 pm V-1. Also, it had the good temporal stability with 80% of its maximum value being retained at the temperature as high as 129 oC
Directed self-assembly of vertical PS-b-PMMA nanodomains grown on multilayered polyelectrolyte films
Kai Liu, Chunming Yang, Boming Yang, Lan Zhang, Wenchao Huang, Xiaoping Ouyang, Fugang Qi, Nie Zhao, Fenggang Bian
Accepted Manuscript , doi: 10.1007/s10118-019-2315-z
[Abstract](7) [PDF 1514KB](3)
Abstract:
Layer-by-layer polyelectrolyte self-assembly, a common method for preparing high-quality ultra-thin films, was employed to direct polystyrene-block polymethylmethacrylate (PS-b-PMMA) block copolymer self-assembly behaviour for the first time. Differing from previous neutral polymer brushes anchored to silicon substrates via chemical modification, polyelectrolyte multilayers (PEMs) were anchored by electrostatic interaction and provided a stable, smooth, and neutral interface. In the present study, PS-b-PMMA was deposited on polyacrylamide hydrochloride/polyacrylic acid (PAH/PAA) PEMs prepared by layer-by-layer self-assembly to successfully yield vertical nanodomains after thermal annealing. Seven layered PEMs revealed an excellent, smooth surface, with a low roughness of 0.6 nm. The periodic structure with interlamellar spacing was determined by grazing-incidence small-angle X-ray scattering (GISAXS) to be 47 nm. The morphology of the PS-b-PMMA nanodomains depended on the polyanion-to-polycation concentration ratio, which is related to the interaction between the block copolymer and the substrate. Our results demonstrate that layer-by-layer self-assembly is a helpful method for the phase separation of block polymers and the fabrication of vertical, ordered nanodomains.
Deactivation Effect Caused by Catalyst-Cocatalyst Pre-Contact in Propylene Polymerization with MgCl2-Supported Ziegler-Natta Catalyst
Zhen Zhang, Baiyu Jiang, Biao Zhang, Zhisheng Fu, Zhiqiang Fan
Accepted Manuscript , doi: 10.1007/s10118-019-2319-8
[Abstract](0) [PDF 1623KB](0)
Abstract:
Propylene slurry polymerization with a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was conducted after different duration of pre-contact of the catalyst with triethylaluminum cocatalyst. The number of active centers ([C*]/[Ti]) was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and measuring sulfur content in the polymer. The pre-contact treatment caused selective deactivation of a part of active centers with low stereoselectivity and much lower activity in the initial stage of polymerization as compared with the polymerization run without the pre-contact stage. The active center concentration and polymerization activity decreased with prolonging of the pre-contact stage. The proportion of stereoselective active centers was increased by prolonging the pre-contact stage, so the isotacticity of produced polypropylene was enhanced. Release of active centers through catalyst particle fragmentation was significantly retarded, and the polymerization rate curve changed from decay type to induction type by the pre-contact treatment. In the induction period both non-stereoselective and stereoselective active centers were released and activated, resulting in gradual reduction of the polymer’s isotacticity in the first 5-10 min of polymerization. Selective deactivation of non-stereoselective active centers also took place in propylene polymerization using the catalyst without pre-contacting with the cocatalyst. In this case the polymerization rate decayed with time after a short induction period of 2-5 min. Over reduction of the active center precursors with low stereoselectivity by triethylaluminum is considered the reason for their deactivation during the pre-contact or the polymerization processes.
Bio-based and Biodegradable Electrospun Fibers Composed of Poly(L-lactide) and Polyamide 4
Tao Chen, Guocheng Zhong, Yuanting Zhang, Liming Zhao, Yongjun Qiu
Accepted Manuscript , doi: 10.1007/s10118-019-2299-8
[Abstract](53) [PDF 1674KB](4)
Abstract:
Novel bio-based and biodegradable block copolymers were synthesized by “click” reaction between poly(L-lactide) (PLLA) and polyamide 4 (PA4). Upon tuning the mole mass of PLLA block, the properties of copolymers and electrospun ultrafine fibers were investigated and compared with those of PLLA and PA4 blends. PLLA and PA4 were found incompatible and formed individual crystalline regions, along with reciprocal inhibition in crystallization. Electrospun fibers were highly hydrophobic, even if the hydrophilic PA4 was rich. The crystallinity of either PLLA or PA4 decreased after electrospinning and PLLA-rich as-spun fibers were almost amorphous. Immersion tests proved that fibers of block copolymers were relatively homogeneous with micro-phase separation between PLLA and PA4. The fibrous structures of copolymers were different from those electrospun from blends, for which sheath-core structure induced by macro-phase separation between homopolymers of PLLA and PA4 was confirmed by TEM, EDS and XPS.
Synthesis of Polyurethane/Poly(urea-formaldehyde) Double-shelled Microcapsules for Self-healing Anticorrosion Coatings
Yan Song, Kaifeng Chen, Jingjing Wang, Yuan Liu, Tao Qi, Guo Liang Li
Accepted Manuscript , doi: 10.1007/s10118-019-2317-x
[Abstract](0) [PDF 2078KB](0)
Abstract:
One-component, catalyst-free self-healing coatings with double-shelled polymer microcapsules have drawn considerable attention due to wide applications. In this work, the synthesis parameters of double-shelled polymer microcapsules and the mechanism of the self-healing process was systematically investigated. Apart from the chemical structure of the microcapsule shell, the thickness of the shell, the size of the microcapsules and the core fraction affect the self-healing anticorrosion properties. The synthesis parameters were further optimized in terms of the agitation rate, pH, weight ratio of core to shell and temperature. Under these conditions, the microcapsule shell consisted of a rough surface formed by poly(urea-formaldehyde) and a smooth inner wall by polyurethane. The size of the microcapsules and core fraction were calculated to be approximately 30 μm and 75%, respectively. The self-healing anticorrosion coating incorporating the as-synthesized microcapsules exhibited corrosion resistance in artificially scratched areas, which were further characterized by electrochemical impedance spectroscopy.
One-Step Production of Continuous Supercapacitor Fibers for a Flexible Power Textile
Yang Hong, Xunliang Cheng, Gejun Liu, Dongsheng Hong, Sisi He, Binjie Wang, Xuemei Sun, and Huisheng Peng
Accepted Manuscript , doi: 10.1007/s10118-019-2301-5
[Abstract](45) [PDF 2633KB](5)
Abstract:
Given that conventional bulky electrochemical energy storage devices are too rigid and heavy to be considered wearable, developing fully integrated power systems are expected to accelerate the successful commercialization of smart electronic textiles. Although great achievements have been made for fiber-shaped energy storage devices, there remains key challenges pertaining to their fabrication efficiency, scalability, and stability. Herein, a general and highly efficient method is found to continuously fabricate supercapacitor fibers with lengths of kilometers at high production rate up to 118 m/h through a simple one-step wet spinning method. Beneficial from the designed unique two-circle-in-one-circle architecture, the resulting supercapacitor fibers demonstrated high electrochemical stability even after being bended for 100,000 cycles. As a demonstration, these continuous supercapacitor fibers were further woven into a flexible power scarf for large-scale applications in wearable electronics. This simple and scalable fabrication process combined with the unique structure provides a general and effective paradigm to design the other fiber-shaped devices like sensors, batteries and solar cells.
Computational Design and Fabrication of Enantioselective Recognition Sorbents for L-Phenylalanine Benzyl Ester on Multiwalled Carbon Nanotubes Using Molecular Imprinting Technology
T Sajini, Renjith Thomas, Beena Mathew
Accepted Manuscript , doi: 10.1007/s10118-019-2282-4
[Abstract](50) [PDF 2709KB](5)
Abstract:
Computational strategies have been suggested to investigate the influence of the nature of monomers and cross-linker for the design of three dimensional imprinted polymers with selective recognition sites for L-phenylalanine benzyl ester (L-PABE) molecule. Here computational chemistry methods were applied to screen the moles of functional monomer that interacts with one mole of the template molecule. Effect of the nature of functional monomer, cross-linker and mole ratio were determined computationally using Density Functional calculations with B3LYP functional and generic 6-31G basis set. Methacrylic acid (MAA) and ethyleneglycol dimethacrylate (EGDMA) were used as the functional monomer and crosslinking agent respectively. L-PABE imprinted polymer layered on multiwalled carbon nanotube (MWCNT) and conventional bulk MIP were also synthesised and characterized. To investigate the influence of pre-organization of binding sites on the selectivity of L-PABE, respective non-imprinted polymers were also synthesised. MWCNT-MIPs and MIPs exhibit the highest adsorption capacity towards L-PABE. The synthesized polymers revealed characteristic adsorption features and selectivity towards L-PABE in comparison with its enantiomer analogues.
Block Copolymer Colloidal Particles with Unique Structures through Three-Dimensional Confined Assembly and Disassembly
Jiangping Xu and Jintao Zhu
Accepted Manuscript , doi: 10.1007/s10118-019-2294-0
[Abstract](45) [PDF 4086KB](0)
Abstract:
Structured block copolymer (BCP) particles have gained increasing attention due to their potential applications in separation, catalysis, controlled release and other fields. Three-dimensional confined assembly has been proved as a facile yet robust approach for generating BCP particles with controllable shapes and internal structures. In this feature paper, we summarized the preparation of structured polymeric particles through three-dimensional (3D) confined self-assembly of BCPs. The effects of interfacial interactions, degree of confinement, and additives on the shape and internal structure of BCP microparticles were comprehensively discussed. In addition, we highlighted the recent progress in using disassembly as a route to synthesize colloidal particles with unique structures. Two strategies were introduced in this part: a) disassembling the discrete domains resulted in mesoporous microparticles; b) while disassembling the continuous domains led to the dissociation of microparticles into micelle-like nano-objects. The applications of the structured colloidal particles in photonic crystals, controlled release, and directed growth of inorganic materials, were also presented. Finally, we discussed the current challenges and future opportunities in this promising area.
Synthesis of an Azobenzene-Containing Main-Chain Crystalline Polymer and Photodeformation Behaviors of Its Supramolecular Hydrogen- Bonded Fibers
Zhengzheng Wang and Huiqi Zhang
Accepted Manuscript , doi: 10.1007/s10118-019-2302-4
[Abstract](37) [PDF 975KB](8)
Abstract:
The synthesis of a new azobenzene (azo)-containing main-chain crystalline polymer with reactive secondary amino groups in its backbone and photodeformation behaviors of its supramolecular hydrogen-bonded fibers are described. This main-chain azo polymer (namely Azo-MP6) was prepared via the first synthesis of a diacrylate-type azo monomer and its subsequent Michael addition copolymerization with trans-1,4-cyclohexanediamine under the mild reaction condition. Azo-MP6 was found to have a linear main-chain chemical structure instead of a branched one, as verified by comparing its 1H NMR spectrum with the 1H NMR spectrum of the azo polymer prepared via the polymer analogous reaction of Azo-MP6 with acetic anhydride. The thermal stability, phase transition behavior, and photoresponsivity of Azo-MP6 were characterized with TGA, DSC, POM, XRD, and UV-vis. The experimental results revealed that it has good thermal stability, low glass transition temperature, broad crystalline phase temperature range, and highly reversible photoresponsivity. Physically crosslinked supramolecular hydrogen-bonded fibers with good mechanical properties and a high alignment order of azo mesogens were readily fabricated for Azo-MP6 by using the simple melt spinning method, and they could show “reversible” photoinduced bending under the same UV light irradiation and good anti-fatigue properties.
Synthesis and Properties of Photodegradable Poly(furan-amine)s by a Catalyst-Free Multicomponent Cyclopolymerization
Weiqiang Fu, Guinan Zhu, Jianbing Shi, Bin Tong, Zhengxu Cai, and Yuping Dong
Accepted Manuscript , doi: 10.1007/s10118-019-2281-5
[Abstract](86) [PDF 956KB](17)
Abstract:
A series of new photodegradable poly(furan-amine)s (PFAs) were synthesized by a one-pot, catalyst-free, multicomponent cyclopolymerization between diisocyanides, dialkylacetylene dicarboxylates, and aromatic dialdehydes. All polymerizations were conducted in toluene at 100 °C for 6 h without inert gas protection and furnished polymers with a satisfactory molecular weight (Mw up to 32200) and yield. The PFA structure was confirmed by spectroscopic techniques, such as GPC, FT-IR, and NMR, as well as by comparison with a model compound. The polymers exhibited good solubility in common organic solvents and thermal stability. All the PFAs had high refractive indices in the visible light region (400 to 900 nm). Moreover, the PFAs were substantially degraded by UV irradiation due to the presence of furan rings. The film thickness reduction rate could be over 90%.
Nanoparticle Dispersion and Glass Transition Behavior of Polyimide-Grafted Silica Nanocomposites
Shani Hu, Yu Lin, Guozhang Wu
Accepted Manuscript , doi: 10.1007/s10118-019-2300-6
[Abstract](68) [PDF 1347KB](7)
Abstract:
How to control the spatial distribution of nanoparticles to achieve different performance requirements is a constant challenge in the field of polymer nanocomposites. Current studies have been focused on the flexible polymer chain systems. In this study, the rigid polyimide (PI) chain grafted silica particles with different grafting chain lengths and grafting density were prepared by “grafting to” method, and the influence of polymerization degree of grafted chains (N), matrix chains (P) and grafting density (σ) on the spatial distribution of nanoparticles in the PI matrix was reported. Besides, the glass transition temperature (Tg) of PI composites was systematically investigated. The results show that silica particles are well dispersed in polyamic acid composite systems, while appear aggregation and small clusters in PI nanocomposites after thermal imide. Besides, the particle size has no impact on the spatial distribution of nanoparticles. When σ·N0.5 << (N/P)2, the grafted and matrix chains interpenetrate, and the frictional resistance of the segment increases, resulting in restricted relaxation kinetics and Tg increase of the PI composite system. In addition, smaller particle size and longer grafted chains are beneficial for improving Tg of composites. These results are all propitious to complete the microstructure control theory of nanocomposites and make a theoretical foundation for the high performance and multi-function of PI nanocomposites.
Monolithic Covalent Organic Framework Aerogels through Framework Crystallization Induced Self-Assembly: Heading towards Framework Materials Synthesis over All Length Scales
Wei Zhao, Tianpin Wang, Jiali Wu, Ruping Pan, Xiangyang Liu and Xikui Liu
Accepted Manuscript , doi: 10.1007/s10118-019-2313-1
[Abstract](9) [PDF 2660KB](8)
Abstract:
Here through the synergism between kinetic dynamic imine-exchange control and thermodynamic control, rarely observed compressible, porous, crystalline COF aerogels were synthesized, the mechanism behind is a framework crystallization induced self-assembly (FCISA) process. The prepared COF aerogel possess extremely high BET surface over 2000 m2/g and high maximum equilibrium adsorption capacity of bisphenol-A as 699 mg/g in aqueous solution.
Fluorescent Supramolecular Polymersomes Based on Pillararene/Paraquat Molecular Recognition for pH-Controlled Drug Release
Run Zhao, Yujuan Zhou, Kecheng Jie, Jie Yang, Sébastien Perrier, Feihe Huang
Accepted Manuscript , doi: 10.1007/s10118-019-2305-1
[Abstract](27) [PDF 4860KB](2)
Abstract:
Researchers have put significant efforts on developing versatile fluorescent polymeric systems due to their promising biological/biomedical labelling, tracking, monitoring, imaging, and diagnostic applications. However, complicated organic/polymeric synthesis or post modification of these functionalized platforms is still a big obstacle for their further application and thereby provides clear motivation for exploring alternative strategies for the design and fabrication of easily available fluorescent systems. The marriage of supramolecular polymers and fluorescent imaging can provide a facile and dynamic manner instead of tedious and time-consuming synthesis due to the dynamic and reversible nature of noncovalent interactions. Herein, based on water-soluble pillararene/paraquat molecular recognition, we successfully prepare two amphiphilic polypseudorotaxanes which can self-assemble into supramolecular polymersomes in water. These polymersomes can be reversibly destroyed and reformed by tuning the solution pH. Attributing to the aggregation-induced emission of tetraphenylethylene groups, high fluorescence can be introduced into the obtained supramolecular polymersomes. Furthermore, pH-triggerd release of an encapsulated water-insoluble drug (doxorubicin) from the self-assembled fluorescent supramolecular polymersomes is also investigated.
(Arylimido)vanadium(V)-Alkylidene Complexes as Catalysts for Ring-Opening Metathesis Polymerization (ROMP) of Cyclic Olefins: Ligand Design for Exhibiting the High Activity
Kotohiro Nomura and Sapanna Chaimongkolkunasin
Accepted Manuscript , doi: 10.1007/s10118-019-2298-9
[Abstract](47) [PDF 1277KB](1)
Abstract:
(Imido)vanadium(V)-alkylidene complexes of type, V(CHSiMe3)(NR)(OR’)(PMe3)2 [R = Ad, C6H5, 2,6-Me2C6H3, 2,6-Cl2C6H3; R’ = 2,6-Me2C6H3, 2,6-iPr2C6H3, 2,6-F2C6H3, C6F5, C6Cl5], exhibited from moderate to remarkable catalytic activities for ring-opening metathesis polymerization (ROMP) of norbornene (NBE). The catalytic activities were affected by the ligand substituents, and V(CHSiMe3)(N-2,6-Cl2C6H3)(OC6X5)(PMe3)2 (X = F, Cl) demonstrated the exceptionally high catalytic activities for ROMP of NBE. The complexes polymerized cycloheptene (CHPE) and cis-cyclooctene (COE), and the ROMP of COE by the OC6Cl5 analogue proceeded in a living manner even at 80 ºC, and the activity increased with increasing the temperature up to 120 ºC. Highly active catalysts for ROMP of cyclic olefins (NBE, cyclopentene, CHPE) can be generated in situ by premixing isolated V(CHSiMe3)(NC6F5)(O-2,6-iPr2C6H3)(PMe3)2 with 1.0 equiv of C6F5OH or C6Cl5OH via the immediate phenoxy exchange; the activity was affected by the kind of phenol added [TOF in the ROMPs of NBE: 46200 min-1 (upon addition of C6F5OH) vs 37.3 min-1 (none)].
Non-Fullerene Acceptors with a Thieno[3,4-c]pyrrole-4,6-dione (TPD) Core for Efficient Organic Solar Cells
Shizhe Geng, Weitao Yang, Jian Gao, Shuixing Li, Minmin Shi, Tsz-Ki Lau, Xinhui Lu, Chang-Zhi Li, and Hongzheng Chen
Accepted Manuscript , doi: 10.1007/s10118-019-2309-x
[Abstract](13) [PDF 1247KB](3)
Abstract:
To achieve the red-shifted absorptions and appropriate energy levels of A-D-A type non-fullerene acceptors (NFAs), in this work, we design and synthesize two new NFAs, named TPDCIC and TPDCNC, whose electron-donating (D) unit is constructed by a thieno[3,4-c]pyrrole-4,6-dione (TPD) core attached to two cyclopentadithiophene (CPDT) moieties at both sides, and the electron-accepting (A) end-groups are 2-(3-oxo-2,3-dihydroinden-1-ylidene) malononitrile (IC) and 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile (NC), respectively. Benefiting from TPD core, which easily forms quinoid structure and O···H or O···S intramolecular noncovalent interactions, TPDCIC and TPDCNC show more delocalization of π-electrons and perfect planar molecular geometries, giving the absorption ranges extended to 822 nm and 852 nm, respectively. Furthermore, the highest occupied molecular orbital (HOMO) levels of TPDCIC and TPDCNC remain relatively lower-lying due to the electronegativity of the carbonyl groups on TPD core. Considering that the absorptions and energy levels of the two NFAs match well with those of a widely used polymer donor, PBDB-T, we fabricate two kinds of organic solar cells (OSCs) based on the PBDB-T:TPDCIC and PBDB-T:TPDCNC blended films, respectively. Through a series of optimizations, the TPDCIC-based devices yield an impressing power conversion efficiency (PCE) of 10.12% with a large short-circuit current density (JSC) of 18.16 mA cm-2, and the TPDCNC-based ones exhibit a comparable PCE of 9.80% with a JSC of 17.40 mA cm-2. Our work is the first report of the TPD-core-based A-D-A type NFAs, providing a good reference for the molecular design of high-performance NFAs.
Mechanism of Janus polymerization: A DFT study
Tianwen Bai, Xufeng Ni, Jun Ling, Zhiquan Shen
Accepted Manuscript , doi: 10.1007/s10118-019-2318-9
[Abstract](0) [PDF 1039KB](0)
Abstract:
Janus polymerization is featured as a combination of cationic and anionic growing ends in one living polymer chain. In the copolymerization of THF and CL catalyzed by lutetium triflates and initiated by propylene oxide, three stages are identified by kinetic study including (1) fast cationic polymerization with slow anionic one, (2) fast anionic polymerization with dormant cationic one, and (3) reactivation of cationic polymerization with coupling of anionic and cationic chain ends. In this work, density functional theory (DFT) calculation is employed to investigate the reaction details of ionic polymerization and dormancy. A “tripedal crow” configuration is proposed to illustrate unique high-coordinated ligand exchange configuration in anionic polymerization in different stages. The trigger of dormancy is determined as chain structures rather than concentration of triflate anion according to both calculation and experimental results.
Efficient Addition Polymerization of Norbornene with Polar Norbornene Derivatives by Neutral Nickel (II) Catalysts
Ling Guo, Yan-Ping Zhang, Hong-Liang Mu, Li Pan, Kai-Ti Wang, Huan Gao, Bin Wang, Zhe Ma, Yue-Sheng Li
Accepted Manuscript , doi: 10.1007/s10118-019-2292-2
[Abstract](57) [PDF 932KB](3)
Abstract:
A series of nickel complexes {4a: [(2,6-iPr2C6H3)N=CHC16H12O]Ni(Me)(Py), 4b:[(2,6-iPr2C6H2OCH3)N=CHC16H12O]Ni(Me)(Py), 4c:[(2,6-iPr2C6H2Cl)N=CHC16H12O]Ni(Me)(Py) and 4d: [(2,6-iPr2C6H2CF3)N=CHC16H12O]Ni(Me)(Py)} based on β-ketiminato ligands bearing various an electron-donating or electron-withdrawing substituent on the para-position of the aniline group were synthesized and unambiguously characterized. The X-ray crystallographic analysis showed that complexes 4b and 4d adopted a near-square-planar geometry, and the anilines bearing a para-OMe or -CF3 group found to be situate on the axial position of the metal center. All complexes exhibited high activities up to 1.251.35 × 107 gPNB⋅molNi-1⋅h-1 toward norbornene (NBE) addition polymerization (conversion > 91.2% in 2 min) under low loading of B(C6F5)3 (B/Ni=3) at 30 C, affording polymers with high molecular weight up to 2.543.18 × 106. Different levels of decrease in catalytic activities could observed of all catalysts as the reaction temperature increased, while 4d bearing a strong electron-withdrawing -CF3 group showed the highest activity at 70 C, while others exhibited notable decrease in catalytic activity with the raise in reaction temperature. Complexes 4a-d showed remarkable tolerance to polar groups and could efficiently promote the copolymerization of NBE with its polar derivatives, including NBE bearing small acetate and hydroxyl group, as well as bulky oligomers, yielding copolymers with high functional NBE incorporations. Novel NBE copolymers with high functional comonomer incorporations and improved solubility were obtained in high yields.

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contents
2019, 37(6) .  
[Abstract](18) [PDF 33847KB](5)
Abstract:
FEATURE ARTICLE
Graphene Fibers: Advancing Applications in Sensor, Energy Storage and Conversion
Guan-Hang Yu, Qing Han, Liang-Ti Qu
2019, 37(6): 535 -547.   doi: 10.1007/s10118-019-2245-9
[Abstract](241) [FullText HTML](78) [PDF 1456KB](29)
Abstract:
Graphene fibers are a kind of novel carbon fibers assembled by orderly aligned graphene sheets with high flexibility, good conductivity, high thermal conductivity, and low density, which make them possible to be widely used in high-performance and multi-functional compound materials as well as flexible electronic devices. In this review, we summarize the research progress in the synthesis of graphene fibers, and their applications in sensor, energy storage, and energy conversion. Furthermore, the current issues and some prospects for the future trend of graphene fibers are discussed.
ARTICLE
Accelerated Cutaneous Wound Healing Using an Injectable Teicoplanin-loaded PLGA-PEG-PLGA Thermogel Dressing
Wei-Ke Xu, Jing-Yu Tang, Zhang Yuan, Cai-Yun Cai, Xiao-Bin Chen, Shu-Quan Cui, Peng Liu, Lin Yu, Kai-Yong Cai, Jian-Dong Ding
2019, 37(6): 548 -559.   doi: 10.1007/s10118-019-2212-5
[Abstract](214) [FullText HTML](100) [PDF 2178KB](18)
Abstract:
Bacterial infection is a very troublesome issue in wound treatment, which stimulates exudate formation and severely delays the healing process. Herein, a thermogelling dressing system composed of two triblock copolymers of poly(D,L-lactic acid-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) with different block lengths was developed to deliver teicoplanin (TPN), a glycopeptide antibiotic, for cutaneous wound repair. The TPN-loaded thermogel was a free-flowing sol at room temperature and formed a semi-solid gel at physiological temperature. In vitro studies demonstrated that the TPN-loaded thermogel system exhibited desired tissue adhesiveness and realized the sustained release of TPN in a fast-followed-slow manner for over three weeks. Furthermore, a full-thickness excision wound model in Sprague-Dawley (SD) rats was constructed to assess the efficacy of TPN-loaded thermogel formulation. Gross and histopathologic observations implied that treatment with the thermogel formulation reduced inflammation response, promoted disposition of collagen, enhanced angiogenesis, and accelerated wound closure and maturity of SD rats. The combination of the bioactivity of TPN and the acidic nature of the thermogel matrix was responsible for such an enhanced wound healing process. Consequently, the TPN-loaded PLGA-PEG-PLGA thermogel is a good candidate of wound dressing for full-thickness excision wound healing.
Electrospun Poly(p-dioxanone)/Poly(ester-urethane)ureas Composite Nanofibers for Potential Heart Valve Tissue Reconstruction
Juan Du, Ji-Hu Wang, Hai-Yan Yu, Yan-Yan Zhang, Li-Hui Pu, Jin-Cheng Wang, Shu-Yang Lu, Si-Hao Chen, Tong-He Zhu
2019, 37(6): 560 -569.   doi: 10.1007/s10118-019-2231-2
[Abstract](203) [FullText HTML](104) [PDF 1577KB](16)
Abstract:
Electrospun nanofibrous mats represent a new generation of medical textiles with promising applications in heart valve tissue reconstruction. It is important for biomaterials to mimic the biological and mechanical microenvironment of native extracellular matrix (ECM). However, the major challenges are still remaining for current biomedical materials, including appropriate mechanical properties, biocompatibility, and hemocompatibility. In the present work, the novel composite nanofibrous mats of poly(p-dioxanone) (PDO) and poly(ester-urethane)ureas (PEUU) are fabricated by electrospinning system. The optimal combination ratio of PDO to PEUU may balance the mechanical properties and cellular compatibility to match the newly formed tissue. In PDO/PEUU composite nanofibrous mats, PEUU can provide the biomimetic elastomeric behavior, and PDO could endow the excellent biocompatibility. In comparison to nanofibrous mat of neat PDO, the composite showed significantly improved mechanical properties, with 5-fold higher initial elongation at break. Furthermore, human umbilical vein endothelial cells (HUVECs) were cultured on the composite to evaluate its ability to rapidly endothelialize as heart valve tissue engineering. The results revealed that PDO/PEUU composite nanofibrous mats could promote cell adhesion and proliferation, especially for the ratio of 60/40. Overall, PDO/PEUU composite nanofibrous mats (60/40) show the excellent mechanical properties, appropriate biocompatibility and hemocompatibility which meet the necessary norm for tissue engineering and may be suitable for potential heart valve tissue reconstruction.
Substituent Effects of Pyridyl-methylene Cyclopentadienyl Rare-earth Metal Complexes on Styrene Polymerization
Zhen Zhang, Zhong-Yi Cai, Yu-Peng Pan, Yan-Li Dou, Shi-Hui Li, Dong-Mei Cui
2019, 37(6): 570 -577.   doi: 10.1007/s10118-019-2209-0
[Abstract](181) [FullText HTML](92) [PDF 673KB](6)
Abstract:
Salt metathesis reactions between pyridyl-methylene-cyclopentadienyl lithium salt and LnCl3 followed by the addition of two equivalents of LiCH2SiMe3 afforded a series of constrained-geometry-configuration rare-earth metal bis(alkyl) complexes (Cp′CH2-Py)Ln(CH2SiMe3)2(THF)n (Py = C5H4N, Cp′ = C5H4 (Cp), Ln = Sc, n = 0 (1); Cp′ = C9H6 (Ind), Ln = Sc, n = 0 (2); Cp′ = 3-Me3Si-C9H5 (3-Me3Si-Ind), Ln = Sc, n = 0 (3a), Ln = Lu (3b), Y (3c), n = 1; Cp′ = 2,7-(tBu)2C13H8 (2,7-(tBu)2-Flu), Ln = Sc (4a), n = 0, Ln = Lu (4b), Y (4c), n = 1) in moderate to good yields, which were characterized by NMR spectroscopy and single-crystal X-ray diffraction (for complex 3a). In the presence of [Ph3C][B(C6F5)4] and AliBu3, these complexes displayed different performances towards styrene polymerization. Rare-earth metal bis(alkyl) precursors bearing Cp, Ind, and 3-Me3Si-Ind segments exhibited very low catalytic activity to afford syndiotactic polystyrene. All electron-donating tBu substituted complexes 4a, 4b, and 4c showed very high activity and perfect syndiotactivity (rrrr > 99%), producing high molecular weight polystyrene (up to 54.1 × 104) with relatively narrow molecular distribution (PDI = 1.28−2.49).
Ethylene-bridged Indenyl-fluorenyl Metallocene Complexes for Efficient Preparation of Allyl-terminated Propylene Oligomers and Polymers via Selective β-Methyl Transfer
Lei Zhang, Bin Zhang, Haiyan Ma
2019, 37(6): 578 -590.   doi: 10.1007/s10118-019-2224-1
[Abstract](269) [FullText HTML](104) [PDF 1036KB](14)
Abstract:
Four C1-symmetric ansa-metallocene complexes, C2H4(Ind)(2,7-tBu2-Flu)ZrCl2 (4), C2H4(3-Bn-Ind)(2,7-tBu2-Flu)ZrCl2 (5), C2H4(3-Bn-Ind)(3,6-tBu2-Flu)ZrCl2 (6), and C2H4(3-Bn-Ind)(2,7-tBu2-Flu)HfCl2 (7), were synthesized and characterized. The structures of complexes 4, 5, and 7 were further determined via X-ray diffraction studies. Upon activation with modified methylaluminoxane (MMAO) or AliBu3/[Ph3C][B(C6F5)4] (TIBA/TrB), most of these complexes showed high efficiency in catalyzing propylene oligomerization/polymerization to afford products dominantly with allyl terminals via selective β-methyl transfer (β-Me transfer). The introduction of 3-benzyl group on the indenyl ring of the complexes was found to be crucial in enabling highly selective β-Me transfer during the polymerization process, leading to selectivities up to 89% obtained by zirconocene complexes 5 and 6, and up to 91% obtained by hafnocene complex 7. Detailed chain-end analysis by 1H-NMR, 13C-NMR, and MALDI-TOF mass spectroscopy revealed that the allyl chain-ends of the polymeric products resulted from a selective β-Me transfer process after two successively primary insertions of the monomer. Further studies concerning the dependence of chain release selectivity as well as the molecular weight of products on monomer concentration suggested that both β-Me transfer (major) and β-hydrogen transfer (β-H transfer) (minor) mediated by 5/MMAO and 6/MMAO systems may mainly operate in a bimolecular pathway.
Controlled Polymerization of Methyl Methacrylate and Styrene via Cu(0)-Mediated RDRP by Selecting the Optimal Reaction Conditions
Yong-Peng Miao, Jing Lyu, Hai-Yang Yong, Sigen A, Yong-Sheng Gao, Wen-Xin Wang
2019, 37(6): 591 -597.   doi: 10.1007/s10118-019-2236-x
[Abstract](165) [FullText HTML](79) [PDF 406KB](10)
Abstract:
Cu(0)-mediated reversible deactivation radical polymerization (Cu(0)-mediated RDRP) has been demonstrated as an excellent technique to control the polymerization of multiple vinyl monomers (e.g., acrylates, methacrylates, and styrene). However, the complexity of the reaction mechanism and multi-component system nature make it challenging to choose the appropriate conditions and consider the factors of achieving controllable polymerization when switching from one monomer to others with different reactivities. Herein, by polymerizing two examplary monomers: methyl methacrylate (MMA) and styrene via Cu(0)-mediated RDRP under different conditions, we have found that the reaction parameters (e.g., initiator, ligand, solvent, and deactivator) play a crucial role in regulating two equilibriums: (i) mutual conversion of different copper species which determines the relative concentration of Cu(I) and Cu(II), and (ii) polymerization equilibrium which is the combination of activation/deactivation, propagation and termination processes. We have demonstrated that by taking both the mutual conversion of different copper species and the polymerization equilibrium into account, the optimal reaction conditions could be selected, and the well-controlled Cu(0)-mediated RDRPs of methyl methacrylate and styrene were achieved with narrow molecular weight distributions and predicted molecular weight.
Polymerization Mechanism of Methyl Methacrylate Initiated by Ethyl Acetate/t-BuP4
De-Yong Xia, Qi-Min Jiang, Wen-Yan Huang, Hong-Jun Yang, Xiao-Qiang Xue, Li Jiang, Bi-Biao Jiang
2019, 37(6): 598 -603.   doi: 10.1007/s10118-019-2228-x
[Abstract](176) [FullText HTML](126) [PDF 669KB](10)
Abstract:
The anionic polymerization of methyl methacrylate (MMA) was carried out using phosphazene base t-BuP4 and ethyl acetate (EA) as the catalyst and the initiator, respectively. Gas chromatography (GC), size exclusion chromatography (SEC) measurements, and nuclear magnetic resonance (NMR) analyses were used to reveal the polymerization mechanism and to confirm the polymer structure. The results confirmed the proposed polymerization mechanism and the polymer structure, while the initiator efficiency was low. Meanwhile, the initiation by methoxy anion coming from hydrolysis of the ester bond in MMA was also observed. As a result, there is a marked deviation between the theoretical molecular weight and the measured molecular weight, and it is essential to carry out the polymerization at excessive dosage of t-BuP4 for preparing polymers with narrow molecular weight distribution.
Langmuir-Blodgett Films of C60-end-capped Poly(ethylene oxide)
Ke Ou, Xian Xu, Yu Shao, Wei-Jie Wang, Wen-Bin Zhang, Shu-Guang Yang
2019, 37(6): 604 -608.   doi: 10.1007/s10118-019-2234-z
[Abstract](160) [FullText HTML](71) [PDF 503KB](6)
Abstract:
Buckyballs (C60) are linked to one end and two ends of linear poly(ethylene oxide) (PEO) chains through highly efficient click chemistry to obtain giant amphiphilic molecules C60-PEO and C60-PEO-C60, respectively. C60-PEO and C60-PEO-C60 molecules are spread on water surface and then transferred to solid substrates with Langmuir-Blodgett (LB) film deposition approach. C60-PEO and C60-PEO-C60 exhibit fractal growth behavior on the solid substrate under certain conditions owing to the crystallization ability of PEO segment. PEO chain length and the end capped mode both affect the fractal growth pattern.
Superhydrophobic PVDF/TiO2-SiO2 Membrane with Hierarchical Roughness in Membrane Distillation for Water Recovery from Phenolic Rich Solution Containing Surfactant
N. Hamzah, C. P. Leo, B. S. Ooi
2019, 37(6): 609 -616.   doi: 10.1007/s10118-019-2235-y
[Abstract](188) [FullText HTML](85) [PDF 1254KB](6)
Abstract:
Superhydrophobic poly(vinylidene fluoride) (PVDF) membrane incorporated with nanoparticles was applied in membrane distillation to recover water from phenolic rich solution containing surfactant. The membranes coated on woven support were fabricated using phase inversion with dual bath coagulation and post-modified using silane. The membranes incorporated with TiO2, SiO2, or a mixture of TiO2-SiO2 nanoparticles achieved the water contact angle higher than 160°. The addition of TiO2-SiO2 mixture into PVDF matrix further enhanced the hierarchical roughness of membrane. Hence, PVDF/TiO2-SiO2 membrane achieved the highest permeation flux and rejected 99.9% of gallic acid in the feed (100 g/L). PVDF/TiO2-SiO2 membrane also maintained a relative flux (J/J0) higher than 0.9 after 8 h of operation. Even with the presence of surfactant in phenolic rich solution, PVDF/TiO2-SiO2 membrane was able to exhibit relative flux above 0.8. The significant changes on the hydrophobicity and chemical properties of PVDF/TiO2-SiO2 membrane due to fouling were not observed after 50 h of static adsorption test.
Isothermal Crystallization of iPP in Environment-friendly Diluents: Effect of Binary Diluents and Crystallization Temperature on Crystallization Kinetics
Yu-Jie Wang, Su-Ying Yan, Zhi-Ping Zhao, Zhen-Yu Xi
2019, 37(6): 617 -626.   doi: 10.1007/s10118-019-2219-y
[Abstract](160) [FullText HTML](106) [PDF 1048KB](8)
Abstract:
The growing demand for non-toxic solvents for membrane preparation has motivated the studies for green and sustainable alternatives of solvents. The effect of droplet isothermal growth within the liquid-liquid phase separation region on isothermal spherulitic growth rate of isotactic polypropylene (iPP) was investigated. The results showed that the droplets grew up at a rate of 0.0172 μm·s−1. The larger droplets slowed down the isothermal spherulitic growth rate of iPP. Higher mass ratio of carnauba wax (Cwax)/soybean oil (SO) resulted in faster droplet growth due to weak interaction with polymers. The isothermal crystallization behaviors of iPP in environment-friendly binary diluents consisting of Cwax and SO mixture were further investigated experimentally using polarized optical microscopy. It was demonstrated that the isothermal spherulitic growth rate of iPP in diluents decreased nonlinearly with the increasing crystallization temperature. Compared with virgin iPP, isothermal spherulitic growth rate of iPP in SO diluent was significantly slowed down. The spherulitic growth was further retarded after the addition of Cwax in mixed diluents, resulting in a lower crystallization rate than that in SO. Moreover, the crystal form of iPP membranes was found to be α type through the characterization of small angle X-ray scattering and wide angle X-ray diffraction.
Kinetic Monte Carlo Simulations of Polymer Cold Crystallization
Cheng-Huan Xu, Ji-Ping Wang, Wen-Bing Hu
2019, 37(6): 627 -632.   doi: 10.1007/s10118-019-2222-3
[Abstract](145) [FullText HTML](89) [PDF 707KB](8)
Abstract:
We performed kinetic Monte Carlo simulations of a lattice polymer model holding intramolecular and intermolecular activation barriers for polymer diffusion, on the basis of the previous dynamic Monte Carlo simulations of polymer crystallization. We explored the effective parameter sets for two barriers to freeze the amorphous polymers at low temperatures. The subsequent heating process of the frozen amorphous polymers exhibits clear cold crystallization behaviors. We made preliminary investigation on the crystallinity and the morphology of polymer crystallites yielded during the cold crystallization, which appear in consistence with our common experimental observations. Our present work paves the way for molecular simulations of hot and cold polymer crystallization in the whole temperature range between the glass transition temperature and the melting temperature.