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Quinolinyl Imidazolidin-2-imine Nickel Catalyzed Efficient Copolymerization of Norbornene with para-Chlorostyrene
Yan-Qing Li, Jian Zhou, Ru Xiao, Zheng-Guo Cai
Corrected proof , doi: 10.1007/s10118-020-2400-3
[Abstract](60) [FullText HTML](0) [PDF 371KB](6)
A series of novel quinolinyl imidazolidin-2-imine nickel complexes with different substituents on the imidazolidin-2-imine ligand were synthesized and characterized. The complexes in the presence of methylaluminoxane (MAO) as a cocatalyst catalyzed the copolymerization of norbornene (N) and styrene (S) or para-chlorostyrene (CS) with high activity (up to 1070 kg·mol−1·h−1). The installation of sterically bulky substituents on the imidazolidine-2-imine ligand was effective for the increase of the molecular weight and the comonomer content, affording high molecular weight copolymers with tunable CS content (0.57 mol%−11.7 mol%), in which the existence of Cl group can provide reaction site for the further functionalization of copolymers as well as the synthesis of graft or cross-linked polymers. The linear relationship between the comonomer content and the glass transition temperature of the copolymers and the monomer reactivity ratios in the copolymerization indicated the formation of the expected functionalized cyclic olefin copolymers (COC).
On-demand Direct Design of Polymeric Thermal Actuator by Machine Learning Algorithm
Bo-En Liu, Wei Yu
Corrected proof , doi: 10.1007/s10118-020-2396-8
[Abstract](41) [FullText HTML](17) [PDF 17572KB](4)
The design optimization of thermal-driven actuators is a challenging task because the performance depends on multiple materials parameters, structural parameters, and working conditions. In this work, we adopted large scale finite element simulation together with machine learning algorithm to fulfill the on-demand design of thermal actuators. Finite element analysis was used to simulate the performance of thermal actuator with two-layer structure, which generated large amount of dataset by considering the variation of parameters including the moduli, thermal expansion coefficient, sample thickness and length, and temperature. Support vector regression (SVR) was adopted to establish the relationship between multiple input parameters and the resulting contact pressure. Thereafter, a simple interior point algorithm was used to achieve the on-demand design based on the SVR model. The contact pressures of thermal actuator constructed from the optimized parameters deviated less than 15% of the target values.
Understanding Self-assembly, Colloidal Behavior and Rheological Properties of Graphene Derivatives for High-performance Supercapacitor Fabrication
Xia-Wei Yun, Bo Tang, Zhi-Yuan Xiong, Xiao-Gong Wang
Corrected proof , doi: 10.1007/s10118-020-2411-0
[Abstract](58) [FullText HTML](24) [PDF 613KB](11)
Graphene derivatives, such as graphene oxide (GO) and reduced graphene oxide (RGO), have been widely used as promising two-dimensional nanoscale building blocks due to their fascinating properties, cost-effective production, and good processability. Understanding the intrinsic self-assembling, colloidal, and rheological features of graphene derivatives is of critical importance to establish the formation-structure-property relationship of graphene-based materials. This article reviews recent progresses in our studies of these interesting properties of graphene derivatives for developing high performance supercapacitors. The content is organized to include characteristics of the dispersions of graphene derivatives, self-assembly of nanosheets from liquid medium, colloidal behavior, rheological properties of the dispersions, processing methods based on the properties, and performance of the fabricated supercapacitors. GO and RGO nanosheets are proved to form different types of assembled structures with unique morphologies, such as ultrathin layer-by-layer films, porous aggregates, and nanoscrolls. The unique rheological properties of GO dispersions and hydrogels, feasible for both the traditional wet-processing and newly-developed technology like three-dimensional printing, are highlighted for their potential in structural manipulation and scalable fabrication of graphene-based devices. The research devoted to up-grading the performance of supercapacitors is presented in some details, which could be applicable for fabricating other graphene-based energy storage devices. Some challenges and perspectives in our point of view are given in the last part of this feature article.
An Electrochemically Stable 2D Covalent Organic Framework for High-performance Organic Supercapacitors
Rashid Iqbal, Amir Badshah, Ying-Jie Ma, Lin-Jie Zhi
Corrected proof , doi: 10.1007/s10118-020-2412-z
[Abstract](87) [FullText HTML](27) [PDF 18903KB](9)
An electrochemically stable two-dimensional covalent organic framework, PI-COF, has been synthesized by a scalable solvothermal method. PI-COF possesses a highly crystalline structure, well-defined pores, high specific surface area, and cluster macrostructure. Thanks to these features, PI-COF can work as electrode materials in organic supercapacitors, exhibiting a specific capacitance of 163 F/g at 0.5 A/g over a wide potential window of 0−2.5 V. Moreover, PI-COF shows excellent rate performance, which can deliver 96 F/g even at a high current density of 40 A/g. Because of the high capacitance and wide potential window, PI-COF has achieved a superior energy density of 35.7 W·h/kg at a power density of 250 W/kg. Most importantly, due to the remarkable electrochemical stability, the PI-COF based device shows outstanding cycling stability with 84.1% capacitance maintained (137 F/g) after 3.0 × 104 charged/discharged cycles at 1 A/g. This work should shed light on designing new COF-based electrode materials for supercapacitors and other electrochemical devices.
Preparation of Titanium-silphenylene-siloxane Hybrid Polymers with High Refractive Index, Transmittance, and Thermal Stability
Dong Zhao, Shu-Xi Shan, Meng Zhang, Xiao-A Zhang, Sheng-Ling Jiang, Ya-Fei Lyu
Corrected proof , doi: 10.1007/s10118-020-2398-6
[Abstract](82) [FullText HTML](25) [PDF 738KB](5)
Vinyl-containing titanium-silphenylene-siloxane oligomers ( O1 , O2 , O3 , and O4 ) with different molar ratios of titanium to silicon were successfully synthesized in high yields by nonhydrolytic sol-gel reaction, and the obtained four oligomers were further crosslinked with methylphenyl hydro-silicone oil ( 4 ) to form corresponding polymers ( P1 , P2 , P3 , and P4 ) by hydrosilylation reaction. Their structures were characterized with spectroscopic characterization techniques including FTIR, 1H-NMR, and Raman spectroscopy. The effect of titanium element on crosslinking behavior, thermal resistance, refractive index, transparency, thermal aging stability, glass transition temperature, and surface properties of the polymers were studied. Compared with titanium-free polymer P1 , the thermal resistance, refractive index, and thermal aging stability of titanium-silphenylene-siloxane polymers ( P2 , P3 , and P4 ) were significantly improved. The titanium-silphenylene-siloxane polymers achieved a high refractive index (n = 1.580−1.584) and thermostability (T5d > 500 °C). In thermal aging, the polymers exhibited superior performances with high optical transparency (~90% at 450 nm) and exhibited high thermal stability (~84% at 450 nm after thermal aging at 150 °C for 120 h). These data indicate that the polymers have potential application in optical materials such as LED encapsulants.
Fiber-shaped Supercapacitors: Advanced Strategies toward High-performances and Multi-functions
Jie Yang, Xue-Lian Li, Jing-Wen Zhou, Bin Wang, Jian-Li Cheng
Corrected proof , doi: 10.1007/s10118-020-2389-7
[Abstract](126) [FullText HTML](32) [PDF 1584KB](11)
Fiber-shaped supercapacitors (FSSCs) show great potential in portable and wearable electronics due to their unique advantages of high safety, environmental friendliness, high performances, outstanding flexibility and integrability. They can directly act as the power sources or be easily integrated with other flexible devices to constitute self-powered and sustainable energy suppliers, providing excellent adaptability to irregular surfaces. This review mainly summarizes the recently reported works of FSSCs including preparation methods of various fiber electrodes, construction strategies of FSSCs and multi-functional device integrations, exploration of reaction mechanisms and strategies to improve the electrochemical performance and provision of suggestions on further designing and optimization of FSSCs. Meanwhile, it shares our perspectives on challenges and opportunities in this field, shedding light on the development of high-performance fiber-shaped supercapacitors with multi-functions.
An Organic Solvent-free Approach towards PDI/Carbon Cloth Composites as Flexible Lithium Ion Battery Cathodes
Dong-Qing Wu, Deng Lu, Peng Yang, Lie Ma, Biao Jiang, Xin Xi, Fan-Cheng Meng, Wen-Bei Zhang, Fan Zhang, Qian-Qian Zhong, Rui-Li Liu
Corrected proof , doi: 10.1007/s10118-020-2388-8
[Abstract](124) [FullText HTML](25) [PDF 1738KB](5)
An acidic solution based method towards flexible lithium ion battery (LIB) cathodes is developed in this work with perylene diimide (PDI) as the electroactive component and carbon cloth (CC) as the current collector. In this approach, PDI is firstly dispersed in concentrated sulfuric acid (H2SO4) and then deposited on CC substrate after the dilution of H2SO4, which provides an organic solvent-free strategy to construct integrated LIB cathodes. The acdic solution based fabrication process also allows the facile adjusting of loading amounts of PDI in the cathodes, which can effectively influence the battery performances of the PDI/CC cathodes. As the result, the acidic solution processed PDI/CC cathode can deliver a high specific capacity of ~ 36 mAh·g−1 at the current density of 50 mA·g−1 in both half cell with lithium foil as anode and full cell with pre-lithiated CC as anode. In both types of the batteries, the PDI/CC cathodes show good cycling stabilities by retaining ~ 84% of the initial capacities after 300 charge-discharge cycles at 500 mA·g−1. Additionally, the excellent mechanical stability of the PDI/CC cathode enables the LIBs in pouch cell to maintain the electrochemical performances under various bending states, demonstrating their potentials for flexible LIBs.
Thermally Conductive and Insulating Epoxy Composites by Synchronously Incorporating Si-sol Functionalized Glass Fibers and Boron Nitride Fillers
Rui-Han Zhang, Xue-Tao Shi, Lin Tang, Zheng Liu, Jun-Liang Zhang, Yong-Qiang Guo, Jun-Wei Gu
Corrected proof , doi: 10.1007/s10118-020-2391-0
[Abstract](151) [FullText HTML](42) [PDF 1227KB](18)
Glass fibers (GFs)/epoxy laminated composites always present weak interlaminar shear strength (ILSS) and low cross-plane thermal conductivity coefficient (λ). In this work, silica-sol, synthesized from tetraethyl orthosilicate (TEOS) and KH-560 via sol-gel method, was employed to functionalize the surface of GFs (Si-GFs). Together with a spherical boron nitride (BNN-30), the thermally conductive BNN-30/Si-GFs/epoxy laminated composites were then fabricated. Results demonstrate that Si-sol is beneficial to the improvement of mechanical properties for epoxy laminated composites (especially for ILSS). The BNN-30/Si-GFs/epoxy laminated composites with 15 wt% BNN-30 fillers display the optimal comprehensive properties. In-plane λ (λ//) and λ reach the maximum of 2.37 and 1.07 W·m−1·K−1, 146.9% and 132.6% higher than those of Si-GFs/epoxy laminated composites (λ// = 0.96 W·m−1·K−1 and λ = 0.46 W·m−1·K−1), respectively, and also about 10.8 and 4.9 times those of pure epoxy resin (λ// = λ, 0.22 W·m−1·K−1). And the heat-resistance index (THRI), dielectric constant (ε), dielectric loss (tanδ), breakdown strength (E0), surface resistivity (ρs) as well as volume resistivity (ρv) are 197.3 °C, 4.95, 0.0046, 22.3 kV·mm−1, 1.8 × 1014 Ω, and 2.1 × 1014 Ω·cm, respectively.
An Overview of Stretchable Supercapacitors Based on Carbon Nanotube and Graphene
Wen-Le Ma, Zhi-Hao Cai, Yi Zhang, Zi-Yuan Wang, Lun Xia, Su-Ping Ma, Guang-Hao Li, Yi Huang
Corrected proof , doi: 10.1007/s10118-020-2386-x
[Abstract](131) [FullText HTML](39) [PDF 1256KB](9)
The wearable demand of modern electronic devices makes flexible and stretchable energy storage device urgently needed. Stretchable and flexible supercapacitors (SCs) are energy storage devices that provide ultrahigh power density while having long-term durability, high security, and electrochemical stability. Among different SCs electrode materials, CNTs and graphene-based materials exhibit great potential in terms of stretchable SCs due to its ultrahigh electrical conductivity, large specific surface area and good mechanical properties. In this review, the state-of-the-art process and achievements in the field of stretchable SCs enabled by CNTs and graphene are presented, which include the novel design strategy, mechanical and electrochemical properties. The final section highlights current challenges and future perspectives on research in this thriving field.
Ionic Liquid/Poly(ionic liquid)-based Semi-solid State Electrolytes for Lithium-ion Batteries
Deng-Zhou Zhang, Yong-yuan Ren, Yin Hu, Liang Li, Feng Yan
Corrected proof , doi: 10.1007/s10118-020-2390-1
[Abstract](207) [FullText HTML](46) [PDF 683KB](12)
Ionic liquids (ILs) have appeared as the most promising electrolytes for lithium-ion batteries, owing to their unique high ionic conductivity, chemical stability and thermal stability properties. Poly(ionic liquid)s (PILs) with both IL-like characteristic and polymer structure are emerging as an alternative of traditional electrolyte. In this review, recent progresses on the applications of IL/PIL-based semi-solid state electrolytes, including gel electrolytes, ionic plastic crystal electrolytes, hybrid electrolytes and single-ion conducting electrolytes for lithium-ion batteries are discussed.
Waste Tire Rubber-based Refrigerants for Solid-state Cooling Devices
Nicolau Molina Bom, Érik Oda Usuda, Mariana da Silva Gigliotti, Denílson José Marcolino de Aguiar, William Imamura, Lucas Soares Paixão, Alexandre Magnus Gomes Carvalho
Corrected proof , doi: 10.1007/s10118-020-2385-y
[Abstract](258) [FullText HTML](64) [PDF 280KB](30)
Management of discarded tires is a compelling environmental issue worldwide. Although there are several approaches developed to recycle waste tire rubbers, their application in solid-state cooling is still unexplored. Considering the high barocaloric potential verified for elastomers, the use of waste tire rubber (WTR) as a refrigerant in solid-state cooling devices is very promising. Herein, we investigated the barocaloric effects in WTR and polymer blends made of vulcanized natural rubber (VNR) and WTR, to evaluate its feasibility for solid-state cooling technologies. The adiabatic temperature changes and the isothermal entropy changes reach giant values, as well as the performance parameters, being comparable or even better than most barocaloric materials in literature. Moreover, pure WTR and WTR-based samples also present a faster thermal exchange than VNR, consisting of an additional advantage of using these discarded materials. Thus, the present findings evidence the encouraging perspectives of employing waste rubbers in solid-state cooling based on barocaloric effects, contributing to both the recycling of polymers and the sustainable energy technology field.
PEDOT: Fundamentals and Its Nanocomposites for Energy Storage
Hong-Wu Chen, Chun Li
Corrected proof , doi: 10.1007/s10118-020-2373-2
[Abstract](245) [FullText HTML](59) [PDF 981KB](23)
PEDOT, or poly(3,4-ethylenedioxythiophene), is among the most successful conducting polymer products because of its stable conductivity, colloidal processability, and rich assembly behavior. Since the very first patents on PEDOT filed in 1988, the material has been widely explored for decades in many applications. In this review, a comprehensive summary on the synthesis, processing and post-treatment of PEDOT will be presented for the sake of the discussion on PEDOT and its nanocomposites for energy storage. Knowing what PEDOT lends itself to the electrode materials is of importance to the rational design of energy storage devices that maximize the real-world performance. Based on these discussions, a roadmap for the development of PEDOT as promising multifunctional electrode component is presented.
Translocation of Heterogeneous Flexible Polymers Assisted by Binding Particles
Wan-Cheng Yu
Corrected proof , doi: 10.1007/s10118-020-2387-9
[Abstract](161) [FullText HTML](60) [PDF 714KB](14)
A polymer chain usually contains two or more types of monomeric species from the perspective of polymer chemistry, which poses a challenge to the understanding of structure-property relationships. It is of course true in the field of polymer translocation. In the present work, I investigate the translocation dynamics of heterogeneous flexible polymers composed of two types of monomers labeled A and B through a nanopore assisted by binding particles (BPs) by using the coarse-grained Langevin dynamics simulations in two-dimensional domains. Specifically, multiblock copolymers with different block lengths and monomeric components are considered. I critically examine how the translocation dynamics responds to the variations in the block length and the monomeric content. Interestingly, it is found that the periodic structure of a multiblock copolymer causes an obvious fingerprint feature in the residence time of individual monomers in which the number of peaks is exactly equal to the number of blocks. These findings provide a basic understanding about the sequence-dynamics relationship for the BPs-assisted translocation of heterogeneous flexible polymers.
An Azoester-containing Photoresponsive Linear Liquid Crystal Polymer with Good Mesophase Stability
Shu-Qiang Han, Ying-Ying Chen, Bo Xu, Jia Wei, Yan-Lei Yu
Corrected proof , doi: 10.1007/s10118-020-2383-0
[Abstract](170) [FullText HTML](63) [PDF 5740KB](14)
Photoresponsive linear liquid crystal polymers (LLCPs) are attractive because of the excellent stimuli-responsibility and the good processability. In this study, a new photoresponsive LLCP containing azoester (PC11AE6) with good mesophase stability was synthesized by ring-opening metathesis polymerization. By introducing photoresponsive azoester mesogenic unit, which has high rigidity and a large length-diameter ratio, the resultant polymer possesses a broad mesophase temperature interval (isotropic temperature = 180 °C). A study on mesophase by 2D-wide angle X-ray diffraction indicated that the mesogens were orientated spontaneously into smectic A phase after annealing. The orientated films and fibres exhibited macroscopic, rapid and reversible deformations under light irradiation as a result of the photoisomerization of azoester as confirmed by UV-Vis absorption spectrophotometry. We anticipate that this work provides a strategy for preparing LLCP with a broad mesophase temperature range, which is positive for potential applications.
Highly Stretchable and Conductive Hybrid Fibers for High-performance Fibrous Electrodes and All-solid-state Supercapacitors
Gui-Qing Wu, Xin-Yu Yang, Jia-Hui Li, Nan Sheng, Cheng-Yi Hou, Yao-Gang Li, Hong-Zhi Wang
Corrected proof , doi: 10.1007/s10118-020-2381-2
[Abstract](128) [FullText HTML](55) [PDF 1118KB](16)
The development of lightweight, flexible, and stretchable energy storage systems is essential for state-of-the-art electronic devices. We propose a new and broad strategy to fabricate a stretchable and conductive GO/CNTs-TPU fiber electrode by direct wet spinning, from which a flexible fibrous supercapacitor is fabricated. The fibrous electrode exhibits a high strength of 11.68 MPa, high conductivity of 342 S/cm, and high specific capacitances (21.8 mF/cm, 36.45 F/cm3, and 95 F/g). The specific capacitance of the assembled all-solid-state hybrid fiber-shaped supercapacitor reaches 14.3 F/cm3. After 5000 charge-discharge cycles, 97% of the capacitance of the hybrid supercapacitor is maintained. These high-strength electrochemical electrode materials could be potential candidates for applications in practical and large-scale energy storage systems and textile clothes.
A High Energy Density Self-supported and Bendable Organic Electrode for Redox Supercapacitors with a Wide Voltage Window
Rashid Iqbal, Aziz Ahmad, Li-Juan Mao, Zahid Ali Ghazi, Abolhassan Imani, Chun-Xiang Lu, Li-Jing Xie, Saad Melhi, Fang-Yuan Su, Cheng-Meng Chen, Lin-Jie Zhi, Zhi-Xiang Wei
Corrected proof , doi: 10.1007/s10118-020-2378-x
[Abstract](252) [FullText HTML](59) [PDF 1239KB](29)
Redox-active organic electrode materials are highly desirable in realizing next-generation all-in-one bendable electronic systems. Herein, a novel flexible supercapacitors (SCs) electrode is fabricated from poly(anthraquinonyl sulfide) (PAQS) and single-walled carbon nanotubes (SWCNTs) suspension by a simple vacuum filtration and named as PAQS-SWCNTs. The PAQS-SWCNTs electrode offered an initial capacitance of 223 F·g−1 and outstanding capacitance retention up to 78.4% after 3 × 104 charge-discharge cycles at 0.5 A·g−1 current density. In a high potential range (0−3 V) and aprotic electrolyte, the PAQS-SWCNTs electrodes in coin cell exhibited an outstanding energy density of 69 Wh·kg−1 at a power density of 90.6 W·kg−1, whereas in the fabricated flexible SCs it retained 63.2 Wh·kg−1. The PAQS-SWCNTs electrodes also showed extraordinary performance at a higher current density (20 A·g−1) and maintained a specific capacitance of 55 and 47 F·g−1 for coin and flexible SCs, respectively. Moreover, the flexible SC is further verified to be able to illuminate up multiple LEDs. These futuristic findings showed that the SCs assembled with flexible PAQS-SWCNTs electrodes have potential application in energy-storage devices and make them highly appealing for future redox supercapacitors.
Three-dimensional Covalent Organic Frameworks as Host Materials for Lithium-Sulfur Batteries
Zhen Li, Hang-Yu Zhou, Fu-Lai Zhao, Tian-Xiong Wang, Xuesong Ding, Bao-Hang Han, Wei Feng
Corrected proof , doi: 10.1007/s10118-020-2384-z
[Abstract](144) [FullText HTML](46) [PDF 473KB](23)
Two reported three-dimensional covalent organic frameworks (3D-COFs), COF-300 and COF-301, which have hierarchical porous structures and large pore volumes, were synthesized and employed as host materials for lithium-sulfur batteries. Owing to possessing excellent porosities as well as abundant hydroxyl groups in the pore walls, COF-301 can not only trap lithium polysulfides (PSs) via physical adsorption inside the pores, but also capture PSs by chemical interactions to relieve the shuttle effect. Interestingly, it is the first time that 3D-COFs were utilized as host materials for lithium-sulfur batteries as well as hydroxyl groups were introduced into COFs for improving the battery performance. As a result, COF-301@S as cathode material could reserve the capacity of 411.6 mA·h·g–1 after 500 cycles with only 0.081% fading per cycle at 0.5 C, exhibiting better battery performance compared with COF-300@S. This study not only expands the applications of 3D-COFs but also provides a new route for designing lithium-sulfur batteries.
Surface Patterning of Self-healing P(MMA/nBA) Copolymer for Dynamic Control Cell Behaviors
Su-Su Liu, Ze-Hong Xiang, Zhi-Fang Ma, Xue-Wen Wu, Qiang Shi, Shing-Chung Wong, Jing-Hua Yin
Corrected proof , doi: 10.1007/s10118-020-2382-1
[Abstract](147) [FullText HTML](43) [PDF 437KB](12)
Cell behaviors are regulated by a dynamic and complex environment characterized by biophysical, mechanical and biochemical properties. However, most works regulate cell behaviors under static conditions or by external factors. To control cell adhesion and proliferation with a dynamic and mechanical environment, we pattern the surface on self-healing copolymer P(MMA/nBA). The copolymer P(MMA/nBA) with the composition of 48/52 (MMA/nBA) recovers nearly 100% of its original tensile strains after 86 h of recovery from deformation. The physical patterns on P(MMA/nBA) film are obtained over large areas and the size of the hole and the width of connecting bar are in line with the copper grid specifications. The patterned surface tends to be flat after 12 h with almost 75%−80% recovery. Compared with cell incubation on polystyrene flat and patterned surface of P(MMA/nBA) film without self-healing capability, the number and morphology of cells are well manipulated on the patterned surface of self-healing P(MMA/nBA) film. This approach provides a convenient method for dynamically regulating the cell behaviors on the surface of self-healing materials without chemical or biological modifications.
Natural Biopolymers for Flexible Sensing and Energy Devices
Muqiang Jian, Yingying Zhang, Zhongfan Liu
Corrected proof , doi: 10.1007/s10118-020-2379-9
[Abstract](367) [FullText HTML](46) [PDF 13257KB](35)
Natural biopolymers feature natural abundance, diverse chemical compositions, tunable properties, easy processability, excellent biocompatibility and biodegradability, as well as nontoxicity, providing new opportunities for the development of flexible sensing and energy devices. Generally, biopolymers are utilized as the passive and active building blocks to endow the flexible devices with mechanical robustness and good biocompatibility. This review aims to provide a comprehensive review on natural biopolymer-based sensing and energy devices. The diverse structures and fabrication processes of three typical biopolymers, including silk, cellulose, and chitin/chitosan, are presented. We review their utilities as the supporting substrates/matrix, active middle layers, separators, electrolytes, and active components of flexible sensing devices (sensors, actuators, transistors) and energy devices (batteries, supercapacitors, triboelectric nanogenerators). Finally, the remaining challenges and future research opportunities are discussed.
Physical Properties of Polymers Under Soft and Hard Nanoconfinement: A Review
Ming-Chao Ma, Yun-Long Guo
Corrected proof , doi: 10.1007/s10118-020-2380-3
[Abstract](187) [FullText HTML](46) [PDF 613KB](27)
Polymeric materials under nanoconfinements have substantially deviated physical properties with respect to the bulk, especially glass transition temperature, physical aging, and crystallization behavior. Here we highlight the leading methods for creating various confinement systems. Upon these systems, recent advances on hard and soft confinement effect for glass transition, physical aging, mechanical properties and crystallization of polymers are reviewed in details. Furthermore, as nanoconfined systems in extreme conditions are experimentally inaccessible, simulation results describing confinement effect on such systems are also discussed.
Tunable Cis-cisoid Helical Conformation of Poly(3,5-disubstibuted phenylacetylene)s Stabilized by nπ* Interaction
Sheng Wang, Si-Liang Cai, Jie Zhang, Xin-Hua Wan
Corrected proof , doi: 10.1007/s10118-020-2376-z
[Abstract](240) [FullText HTML](52) [PDF 619KB](19)
A series of novel cis poly(phenylacetylene)s (PPAs) substituted at meta-position(s) by two alkoxycarbonyl pendants, i.e., sP-Me-C8/rP-Me-C8 , P-Me-C12 , sP-Et-C4 , sP-2C4 and sP-Oct-C4 , were synthesized under the catalysis of [Rh(nbd)Cl]2 (nbd = norbornadiene). The dependence of elongation, screw sense, and stimuli response of helical polyene backbone on the structure of pendant, solvent, and temperature was systematically investigated in both solution and solid states. Because of nπ* interaction between vicinal carbonyl groups, sP-Me-C8/rP-Me-C8 could adopt contracted cis-cisoid helix in THF, toluene, CH2Cl2, and CHCl3. Such an intramolecular interaction was sensitive to the hydrogen bond donating ability of solvent and temperature, but insensitive to the dielectric constant and polarity of solvent. In poly(3-methoxycarbonyl-5-alkoxycarbonylphenylacetylene), the longer the chiral alkyl chain was, the easier the stable cis-cisoid helix could be achieved. However, when the methoxycarbonyl was changed to ethoxycarbonyl, sec-butyloxycarbonyl, and octyloxycarbonyl pendant groups, only cis-transoid helix was obtained at room temperature due to the increased steric hindrance. Moreover, lowering temperature was found to facilitate the stabilization of nπ* interactions, and reversible temperature-dependent stereomutations were achieved in sP-Me-C8 and sP-Et-C4 depending on the solvent where they were dissolved. These results suggested that the long alkyl chain, small pendant size, and lower temperature favored the stabilization of intramolecular nπ* interactions and the formation of contracted, cis-cisoid helices for poly(3,5-diester substituted phenylacetylene)s.
Highly Soluble Polyimides Containing Di-tert-butylbenzene and Dimethyl Groups with Good Gas Separation Properties and Optical Transparency
Chen-Yi Wang, Cai-Rong Jiang, Bin Yu, Xiao-Yan Zhao, Zhao-Liang Cui, Jian Li, Qiang Ren
Corrected proof , doi: 10.1007/s10118-020-2377-y
[Abstract](124) [FullText HTML](48) [PDF 609KB](7)
A rigid aromatic diamine monomer containing di-tert-butylbenzene and dimethyl groups, 3,3′-dimethyl-4,4′-diaminophenyl- 3″,5″-di-tert-butyltoluene, was successfully synthesized by a simple coupling reaction using 3,5-di-tert-butylbenzaldehyde and o-toluidine as starting materials. A series of novel polyimides ( PI 3a3c ) with large pendant groups were prepared with the obtained diamine monomer and three different commercial aromatic dianhydrides (3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride) by one-step high temperature polycondensation. The prepared polyimides exhibited high solubility and good membrane forming ability: they could be dissolved not only in some high boiling solvents such as DMF, NMP, DMAc, and m-Cresol at room temperature, but also in some low boiling solvents such as CHCl3, CH2Cl2, and THF. Their solubility in most solvents could exceed 10 wt%, and the flexible membranes could be obtained by casting their solutions. The prepared membranes exhibited good gas separation properties. The permeability coefficients of PI 3c for CO2 and O2 were up to 124.6 and 42.8 barrer, respectively, and the selectivity coefficients for CO2/CH4 and O2/N2 were 14.7 and 3.3, respectively. The membranes had light color and good optical transmission. Their optical transmittance at 450 nm wavelength was in the range of 67%−79%, and the cutoff wavelength was in the range of 310−348 nm. They also had good thermal properties with glass transition temperature (Tg) values in the range of 264−302 °C. In addition, these membranes possessed good mechanical properties with tensile strength ranging between 77.8−87.4 MPa, initial modulus ranging between 1.69−1.82 GPa, and elongation at break ranging between 4.8%−6.1%.
Antibacterial and pH-responsive Quaternized Hydroxypropyl Cellulose-g-Poly(THF-co-epichlorohydrin) Graft Copolymer: Synthesis, Characterization and Properties
Jin-Rui Deng, Cong-Lei Zhao, Yi-Xian Wu
Corrected proof , doi: 10.1007/s10118-020-2372-3
[Abstract](248) [FullText HTML](143) [PDF 1244KB](19)
The novel quaternized hydroxypropyl cellulose-g-poly(THF-co-epichlorohydrin) graft copolymers, HPC-g-QCP(THF-co-ECH), have been successfully synthesized to combine the properties from hydrophilic hard HPC biomacromolecular backbone and hydrophobic flexible polyether branches. Firstly, the P(THF-co-ECH) living chains were synthesized by cationic ring-opening copolymerization of THF with ECH. Secondly, P(THF-co-ECH) living chains were grafted onto HPC backbone by reaction with ―OH groups along HPC to produce HPC-g-P(THF-co-ECH) graft copolymers. Thirdly, the mentioned graft copolymers were quaternized by reaction with ternary amine to generate functionalized HPC-g-QCP(THF-co-ECH). The HPC-g-QCP(THF-co-ECH) graft copolymers exhibited good antibacterial ability against S. aureus or E. coli bacteria. The ibuprofen (IBU)-loaded microparticles of HPC-g-(QC)P(THF-co-ECH) graft copolymers were prepared by electrospraying. The in vitro pH-responsive drug-release behavior of IBU reached up to 75% of drug-loaded at pH = 7.4. This quaternized graft copolymer was beneficial to solving the problems of a burst effect and fast release of HPC as drug carriers.
Kinematics of Non-axially Positioned Vesicles through a Pore
Yun-Long Han, Ming-Ming Ding, Rui Li, Tong-Fei Shi
Corrected proof , doi: 10.1007/s10118-020-2375-0
[Abstract](267) [FullText HTML](127) [PDF 766KB](5)
We employ finite element method to investigate the kinematics of non-axially positioned vesicles through a pore. To complete the coupling between fluid flow and the vesicle membranes, we use the fluid structure interactions with the arbitrary Lagrangian Eulerian method. Our results demonstrate that the vesicles show different deformations in migration process, in turn an oblique ellipse-shape, slipper-shape, oval-shape. We find that the rotation angle of non-axially positioned vesicles mainly shows the trend of increase, besides the small fluctuation induced by deformation relaxation. Moreover, when the vesicles move towards the axis of the channel, the rotation angle exhibits a decrease because of the decrease of the shear force. However, rotation of axially positioned vesicles hardly occur due to symmetrical shear force. Our results further indicate that the rotation is faster nearby the pore for non-axially positioned vesicles. Our work answers the mapping between the positions of vesicles and deformed states, as well as the change of rotation angle and rotation velocity, which can provide helpful information on the utilization of vesicles in pharmaceutical, chemical, and physiological processes.
Enhanced Crystallization Rate of Poly(L-lactide)/Hydroxyapatite-graft-poly(D-lactide) Composite with Different Processing Temperatures
Min Wang, Lei-Chu You, Yu-Qi Guo, Ni Jiang, Zhi-Hua Gan, Zhen-Bo Ning
Corrected proof , doi: 10.1007/s10118-020-2374-1
[Abstract](287) [FullText HTML](154) [PDF 2987KB](15)
Hydroxyapatite-graft-poly(D-lactide) (HA-g-PDLA) was synthesized by ring-opening polymerization with HA as initiator and stannous octanoate (Sn(Oct)2) as catalyst. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) results indicate that PDLA chains are successfully grafted onto HA particles by covalent bond. Under two different processing temperatures (190 and 230 °C), the effect of the grafted PDLA chains on the crystallization behavior of poly(L-lactide)/HA-g-PDLA (PLLA/HA-g-PDLA) composite was investigated in the current study, comparing to neat PLLA and its four composites (PLLA/HA, PLLA/HA-g-PLLA, PLLA/PDLA, and PLLA/HA/PDLA). The crystallization rate of PLLA/HA-g-PDLA composite is highly enhanced comparing to PLLA, PLLA/HA and PLLA/HA-g-PLLA composites in which there are no stereocomplex (SC) crystallites. In addition, when the processing temperature rises from 190 °C to 230 °C, the acceleration of PLLA crystallization in PLLA/HA-g-PDLA composite is not influenced so much as other composites containing SC crystallites, such as PLLA/HA/PDLA or PLLA/PDLA. The differential scanning calorimetry (DSC) results demonstrate that even without SC crystallites, the crystallization of PLLA can still be accelerated a lot in this composite. This may be related to the interaction between the grafted PDLA chains and the amorphous PLLA chains in PLLA/HA-g-PDLA composite. The isothermal crystallization kinetics studies indicate that the nature of nucleation and crystal growth of PLLA/HA-g-PDLA composite are more likely 3D crystalline growth with heterogeneous nucleation mode, which are different from PLLA or other composites. This investigation could shed new light on the application of PLLA/HA composites.
Conjugated Polymers as Hole Transporting Materials for Solar Cells
Dan Ti, Kun Gao, Zhi-Pan Zhang, Liang-Ti Qu
Corrected proof , doi: 10.1007/s10118-020-2369-y
[Abstract](430) [FullText HTML](164) [PDF 3397KB](20)
In principle, conjugated polymers can work as electron donors and thus as low-cost p-type organic semiconductors to transport holes in photovoltaic devices. With the booming interests in high-efficiency and low-cost solar cells to tackle global climate change and energy shortage, hole transporting materials (HTMs) based on conjugated polymers have received increasing attention in the past decade. In this perspective, recent advances in HTMs for a range of photovoltaic devices including dye-sensitized solar cells (DSSCs), perovskite solar cells (PSCs), and silicon (Si)/organic heterojunction solar cells (HSCs) are summarized and perspectives on their future development are also presented.
Facile Preparation of Electromagnetic Interference Shielding Materials Enabled by Constructing Interconnected Network of Multi-walled Carbon Nanotubes in a Miscible Polymeric Blend
Qi-Yan Zhang, Han-Song Li, Bao-Hua Guo, Zhao-Xia Guo, Jian Yu
Corrected proof , doi: 10.1007/s10118-020-2370-5
[Abstract](366) [FullText HTML](181) [PDF 332KB](35)
Electromagnetic interference (EMI) shielding materials are in great demand in electronic equipment and our surrounding environment to resist the increasing serious radiation pollution. Compared with their metal counterparts, conductive polymer composites (CPCs) have unique advantages of lightweight, corrosive resistance, low cost, and excellent processability, and are therefore an ideal choice for developing high-performance EMI shielding materials. However, CPCs based EMI shielding materials are limited to high filler loading, which caused poor mechanical properties and processability. Here, we demonstrate a facile and highly scalable approach to develop high-performance EMI shielding materials with low filler loading by using miscible poly(phenylene oxide)/polystyrene (PPO/PS) blend as the matrix. In contrast to PS/carbon nanotubes (CNTs) composites, PPO/PS/CNTs composites show much higher EMI shielding effectiveness caused by good dispersion of CNTs and highly interconnected conductive network. An excellent EMI shieling effectiveness of 23−25 dB is achieved for PPO/PS/10%CNTs composites with a thickness of only 375 μm, which is superior to most of reported polymer/CNTs composites prepared by melt-compounding. In addition, the results show that although absorption is the major shielding mechanism, the contribution of reflection is also important and closely related to the connectivity of conductive network, as well as the electrical conductivity of the CPCs.
Side Chain Engineering of Sulfonated Poly(arylene ether)s for Proton Exchange Membranes
Xiang Zhang, Zhi-Wen Li, Xia-Lin Chen, Dong-Yang Chen, Yu-Ying Zheng
Corrected proof , doi: 10.1007/s10118-020-2371-4
[Abstract](312) [FullText HTML](169) [PDF 1154KB](36)
Proton conductivity of proton exchange membranes (PEMs) strongly relies on microscopic morphology, which can be modulated by engineering the distribution of ionic groups. Herein, poly(arylene ether)s with densely distributed allyl functionalities are polymerized from a tetra-allyl bisphenol A monomer. The subsequent thiol-ene addition with sodium 3-mercapto-1-propanesulfonate yields comb-shaped sulfonated fluorinated poly(arylene ether)s (SFPAEs) with ion exchange capacities (IECs) ranging from 1.29 mmol·g−1 to 1.78 mmol·g−1. These SFPAEs exhibit superior proton conductivity over the whole temperature range, which is attributed to the enhanced hydrophilic/hydrophobic phase separation as evidenced by small angle X-ray scattering characterizations. The SFPAE-4-40 with an IEC of 1.78 mmol·g−1 shows the largest proton conductivity of 93 mS·cm−1 at room temperature under fully hydrated condition, higher than that of Nafion 212. Furthermore, the vanadium redox flow battery (VRFB) assembled with SFPAE-4-40 separator exhibits higher energy efficiency than the VRFB assembled with Nafion 212.
Preparation and Characterization of Poly(vinyl alcohol)/ZIF-8 Porous Composites by Ice-templating Method with High ZIF-8 Loading Amount
Xuan-He Yang, Yan-Qing Yao, Mu-Hua Huang, Chun-Peng Chai
Corrected proof , doi: 10.1007/s10118-020-2368-z
[Abstract](270) [FullText HTML](128) [PDF 527KB](20)
A bulk Poly(vinyl alcohol)/ZIF-8 (PVA/ZIF-8) porous composite with aligned porous structure was prepared by ice-templating method. The microstructure of PVA/ZIF-8 porous composites was characterized by scanning electron microscopy (SEM). The results showed that the composites had regular pore structure and ZIF-8 nanoparticles were evenly distributed on the skeleton of PVA. X-ray diffraction (XRD) test results showed that the crystalline structure of ZIF-8 was well preserved in the composites. The specific surface area of the composite was characterized by nitrogen adsorption/desorption test. The specific surface area of the composite was up to 1160 m2·g–1. PVA/ZIF-8 porous composites could also support a certain weight with almost no volume shrinkage. The carbon dioxide adsorption quantity of the composite was up to 11.3 cm3·g–1, proving that PVA/ZIF-8 porous composite has a good application prospect in the field of carbon dioxide adsorption.
Thermal Expansion Behavior of Poly(amide-imide) Films with Ultrahigh Tensile Strength and Ultralow CTE
Lan Bai, Lei Zhai, Min-Hui He, Chang-Ou Wang, Song Mo, Lin Fan
Corrected proof , doi: 10.1007/s10118-020-2366-1
[Abstract](262) [FullText HTML](116) [PDF 558KB](15)
A series of novel poly(amide-imide) (PAI) films with different amide contents were prepared from pyromellitic dianhydride and four amide-containing diamines. These PAI films exhibited excellent mechanical and thermal properties with tensile strength of 203.7−297.4 MPa and Tg above 407 °C. The rigid backbone structures combined with strong intermolecular interactions provided PAI films with ultralow in-plane CTE values from −4.17 ppm/°C to −0.39 ppm/°C in the temperature range of 30−300 °C. The correlation between thermal expansion behavior and aggregation structures of PAI film was investigated. The results suggested that hydrogen bonding interactions could be maintained even at high temperature, thus resulting in good dimension reversibility of films in multiple heating-cooling cycles. It is demonstrated that dimensional stabilities of PAI films are determined by the rigidity, orientation, and packing of molecular chains. Heat-resistant PAI films with ultralow CTE can be developed as flexible substrates by regulating backbones and aggregation structures for optoelectronic application.
Comparative Investigation on Step-cycle Tensile Behaviors of Two Bimodal Pipe-grade Polyethylene with Different Slow Crack Growth Resistance
Yan-Qin Huang, Qing-Long Zhang, Xiao-Ying Lu, Yi-Bin Gong, Hao Zhou, Jia-Chun Feng
Corrected proof , doi: 10.1007/s10118-020-2364-3
[Abstract](232) [FullText HTML](90) [PDF 802KB](9)
In this work, step-cycle tensile behavior of two bimodal polyethylene (PE) materials, a PE100 grade pipe material, XS10, and a PE100-RC (Resistant Crack) grade pipe material, XSC50, was comparatively investigated. By decomposing the strain into a recoverable part and an unrecoverable part, it was found that the deformation recovery capability of XSC50 during stretching was larger than that of XS10. Structural evolution characterized by in situ synchrotron small angle X-ray scattering indicated that the fragmentation of initial crystals in XSC50 occurred at lower strain than in XS10. Considering that XSC50 had relatively small lamellar thickness and similar crystallinity to XS10, we speculated that the larger deformation recovery capability of XSC50 during stretching probably derived from stronger entangled amorphous region caused by larger density of tie molecules and entanglements, which were usually regarded to have a significant influence on the slow crack growth (SCG) resistance of PE materials. As expected, the experimental result of strain hardening modulus test suggested that the deformation recovery capability during stretching was positively correlated with the SCG resistance for XS10 and XSC50 used in this work. The step-cycle tensile test had the potential to be developed into a supplement for comparison of SCG resistance of PE materials.
Single-wavelength Excited Ratiometric Fluorescence pH Probe to Image Intracellular Trafficking of Tobacco Mosaic Virus
Si-Jia Gao, Zhuang Li, Zhi-Cheng Sun, Jin-Yue Wen, Fu-Rong Li, Xiao-Yang Du, Yan Liu, Ye Tian, Zhong-Wei Niu
Corrected proof , doi: 10.1007/s10118-020-2365-2
[Abstract](228) [FullText HTML](90) [PDF 1196KB](7)
As a typical plant virus which has biocompatibility and high transfection efficiency, tobacco mosaic virus (TMV) has shown broad application potential in drug or gene delivery field. Elucidating its intracellular trafficking is of great importance in investigation of its cytotoxicity, targeting site, and delivery efficiency, and is advantageous to designing new TMV-based drug delivery systems with different targets. By taking advantage of the regulated pH value of different organelles in a mammalian cell, we exploit a pH detection strategy to investigate the intracellular trafficking pathway of TMV. Here, we report a single-wavelength excited ratiometric fluorescent pH probe. This probe is constructed by simultaneously coupling pH-sensitive fluorescein isothiocyanate (FITC) and pH-insensitive rhodamine B isothiocyanate (RBIRC) onto the inner surface of TMV. The fluorescence intensity ratio of FITC to RBITC excited at 488 nm responds specifically towards pH value over other interferential agents. By taking use of this single-wavelength excited ratiometric pH probe and confocal laser scanning microscopy, it is shown that the endocytosed TMV is located in a pH decreasing microenvironment and eventually enters lysosomes. This work may provide important guidance on construction of TMV-based nano carriers.
The Role of Mold Temperature on Morphology and Mechanical Properties of PE Pipe Produced by Rotational Shear
Zu-Chen Du, Hao Yang, Xie-Huai Luo, Ze-Xiang Xie, Qiang Fu, Xue-Qin Gao
Corrected proof , doi: 10.1007/s10118-020-2363-4
[Abstract](210) [FullText HTML](102) [PDF 6239KB](6)
The role of mold temperature on the morphology and properties of rotational shearing polyethylene (PE) pipes was studied via a self-developed rotational shear system (RSS). The result indicated that when the mold temperature was 150 °C, the hoop tensile strength and Vicat softening temperature were enhanced rapidly, which were 383.6% and 137.9% higher than those of the conventional PE pipes, respectively. Morphology and crystal structure studies by SEM and DSC revealed that once the rotational shear was applied, the shish-kebab structure began to appear. With the increase of the mold temperature, due to the relaxation of most of the oriented molecular chains, the preservation of shish-kebab structure became difficult. When the mold temperature was 190 °C, only the inner layer of the pipes, where the cooling rate was the largest, could preserve the shish-kebab structure. According to WAXD, there was less shish structure, and the growth of kebab was distorted in the inner layer of the pipes at 210 °C. The result of SAXS suggested that the length of shish changed most within the temperature range from 170 °C to 190 °C. The results of DSC and WAXD showed less change in crystallinity and degree of orientation between the two temperatures. It can be concluded that the reduction of shish length leads to a decrease in mechanical properties and heat-resistance.
Probing Intermittent Motion of Polymer Chains in Weakly Attractive Nanocomposites
Li-Jun Dai, Cui-Liu Fu, You-Liang Zhu, Zhan-Wei Li, Zhao-Yan Sun
Corrected proof , doi: 10.1007/s10118-020-2352-7
[Abstract](324) [FullText HTML](111) [PDF 1485KB](25)
In this study, we investigate the motion of polymer segments in polymer/nanoparticle composites by varying nanoparticle (NP) volume fractions. By studying the probability distribution of segment displacement, segment trajectory, and the square displacement of segment, we find the intermittent motion of segments, accompanied with the coexistence of slow and fast segments in polymer nanocomposites (PNCs). The displacement distribution of segments exhibits an exponential tail, rather than a Gaussian form. The intermittent dynamics of chain segments is comprised of a long-range jump motion and a short-range localized motion, which is mediated by the weakly attractive interaction between NP and chain segment and the strong confinement induced by NPs. Meanwhile, the intermittent motion of chain segments can be described by the adsorption-desorption transition at low particle loading and confinement effect at high particle loading. These findings may provide important information for understanding the anomalous motion of polymer chains in the presence of NPs.
Molecular Mobility in the Amorphous Phase Determines the Critical Strain of Fibrillation in the Tensile Stretching of Polyethylene
Rui Li, Guo-Xing Yang, Ya-Nan Qin, Li Liu, Zhi-Yong Jiang
Corrected proof , doi: 10.1007/s10118-020-2362-5
[Abstract](240) [FullText HTML](104) [PDF 548KB](8)
The microstructural development of bimodal high density polyethylene subjected to tensile deformation was investigated as a function of strain after annealing at different temperatures by means of a scanning synchrotron small angle X-ray scattering (SAXS) technique. Two different deformation mechanisms were activated in sequence upon tensile deformation: intralamellar slipping of crystalline blocks dominates the deformation behavior at small deformations whereas a stress-induced crystalline block fragmentation and recrystallization process occurs at a critical strain yielding new crystallites with the molecular chains preferentially oriented along the drawing direction. The critical strain associated with the lamellar-to-fibrillar transition was found to be ca. 0.9 in bimodal sample, which is significantly larger than that observed for unimodal high-density polyethylene (0.4). This observation is primarily due to the fact that the bimodal sample possesses a greater mobility of the amorphous phase and thereby a reduced modulus of the entangled amorphous network. The conclusion of the mobility of the amorphous phase as a determining factor for the critical strain was further proven by the 1H-NMR T2 relaxation time. All these findings contribute to our understanding of the excellent slow crack growth resistance of bimodal polyethylene for pipe application.
Ethylene Polymerization and Copolymerization with Polar Monomers by Benzothiophene-bridged BPMO-Pd Catalysts
Hong-Liang Mu, Jun-Hao Ye, Guang-Lin Zhou, Kang-Kang Li, Zhong-Bao Jian
Corrected proof , doi: 10.1007/s10118-020-2359-0
[Abstract](284) [FullText HTML](93) [PDF 331KB](13)
A series of new bisphosphine-monoxide (BPMO) ligands based on benzothiophene backbone and the corresponding palladium complexes {к2-2-P(O)(Ph)2-3-PR1R2-C8H4S}PdMeCl { 2a : R1 = R2 = Ph; 2b : R1 = R2 = 2-OMe-Ph; 2c : R1 = R2 = 2-CF3-Ph; 2d : R1 = Ph, R2 = 2-(2′,6′-(OMe)2C6H3)-C6H4} were synthesized and fully characterized by 1H-, 13C-, 31P-, and 2D-NMR spectroscopy and single-crystal X-ray diffraction. In the presence of Na+B[3,5-(CF3)2C6H3]4 (NaBArF), these complexes showed very high activities (up to 2.0 × 107 g·mol–1·h–1) for ethylene polymerization. More significantly, these catalysts enabled the copolymerization of ethylene with a broad scope of commercially available polar comonomers such as acrylates, acrylic acid, acrylonitrile, vinyltrialkoxysilane, allyl acetate, and long-chain 6-chloro-1-hexene to give functionalized polyethylene with reasonable catalytic activities (up to 106 g·mol–1·h–1) and incorporations (up to 5.3 mol%). This contribution suggests that, besides the modulation of conventionally steric and electronic factors, the connectivity (at different linking positions) of BPMO (P,O) donors to the heteroaryl backbone also greatly influences the catalyst properties in terms of catalytic activity, polymer branching content, comonomer scope, and comonomer incorporation.
Fast Computation of Electrostatic Interactions for a Charged Polymer with Applied Field
Hao Lin, Zi-Tong Lei, Ming-Ming Ding, Hong-Jun Wang, Tong-Fei Shi
Corrected proof , doi: 10.1007/s10118-020-2343-8
[Abstract](380) [FullText HTML](104) [PDF 341KB](16)
Using a hybrid simulation approach that combines a finite difference method with a Brownian dynamics, we investigated the motion of charged polymers. Owing to the fact that polymer-solution systems often contain a large number of particles and the charged polymer chains are in a state of random motion, it is a time-consuming task to calculate the electrostatic interaction of the system. Accordingly, we propose a new strategy to shorten the CPU time by reducing the iteration area. Our simulation results illustrate the effect of preset parameters on CPU time and accuracy, and demonstrate the feasibility of the " local iteration” method. Importantly, we find that the increase in the number of charged beads has no significant influence on the time of global iterations and local iterations. For a number of 80 × 80 × 80 grids, when the relative error is controlled below 1.5%, the computational efficiency is increased by 8.7 times in the case that contains 500 charged beads. In addition, for a number of 100 × 100 × 100 grids with 100 charged beads, the computational efficiency can be increased up to 12 times. Our work provides new insights for the optimization of iterative algorithms in special problems.
Molecular Weight Dependence of Associative Behavior in Polyimide/DMF Solutions
Hong-Xiang Chen, En-Song Zhang, Mei Hong, Wei Liu, Xue-Min Dai, Quan Chen, Xue-Peng Qiu, Xiang-Ling Ji
Corrected proof , doi: 10.1007/s10118-020-2358-1
[Abstract](415) [FullText HTML](211) [PDF 428KB](25)
Eight 6FDA-TFDB polyimide (PI) samples with absolute molecular weights ranging from 1.25 × 105 g·mol–1 to 3.11 × 105 g·mol–1 are obtained by precipitation fractionation. Rheological experiments are conducted to determine the influence of molecular weight on the associating behavior of PI in N,N′-dimethylformamide (DMF) solutions in a broad volume fraction, including abnormal steady shear flow, solution heterogeneity, and scaling behavior. Abnormal flow behaviors, i.e., multi-region shear thinning and weak shear thickening, are studied, and these behaviors have not been reported in literature. The heterogeneity of PI/DMF solutions is examined by dynamic rheological test. By plotting ηsp versus ϕ/ϕη, four concentration regions of I–IV can be distinguished for all PI samples with various molecular weights. The scaling results in different concentration regions are in good agreement with the associative polymer theory proposed by Rubinstein and Semenov. The scaling exponents do not show molecular weight dependence in concentration regions I and II. In concentration regions III and IV, the scaling exponents change little when the molecular weight is below 242 k but increase when the molecular weight increases from 242 k to 311 k. This work can help us to understand polyimide solution properties from dilute to semidilute entangled solutions, and will guide the polyimide solution preparation for different processing.
Preparation of Polyaniline-coated Composite Aerogel of MnO2 and Reduced Graphene Oxide for High-performance Zinc-ion Battery
Jing Mao, Fang-Fang Wu, Wen-Hui Shi, Wen-Xian Liu, Xi-Lian Xu, Gang-Feng Cai, Yi-Wen Li, Xie-Hong Cao
Corrected proof , doi: 10.1007/s10118-020-2353-6
[Abstract](327) [FullText HTML](123) [PDF 947KB](16)
Aqueous zinc-ion batteries, especially Zn-MnO2 battery, have attracted intensive attention owing to their unique features of high capacity, environmental friendliness, and safety. However, the problem of Mn dissolution hinders the development of zinc-ion batteries with long-term usage and high-rate performance. In this work, a novel preparation method for the polyaniline (PANI)-coated composite aerogel of MnO2 and rGO (MnO2/rGO/PANI) electrode is reported. The obtained composite possesses high electrical conductivity, and also effectively suppresses the dissolution of Mn. The fabricated MnO2/rGO/PANI//Zn battery exhibits a high capacity of 241.1 mAh·g−1 at 0.1 A·g−1, and an excellent capacity retention of 82.7% after 600 charge/discharge cycles. In addition, the rapid diffusion coefficient of the MnO2/rGO/PANI electrode was further examined by galvanostatic intermittent titration technique. This work provides new insights into the development of high-performance Zn-MnO2 battery with a better understanding of its diffusion kinetics.
A new evaluation criterion for optimizing the mechanical properties of toughened polypropylene/silica nanocomposites
Hossein Pourrahmani, Mona Golparvar, Mohammad Fasihi
Accepted Manuscript , doi: 10.1007/s10118-020-2399-5
[Abstract](59) [PDF 2365KB](10)
This study aims to experiment with the mechanical properties of polypropylene (PP)/thermoplastic elastomer/nano-silica/compatibilizer nanocomposite using the melt mixing method. The addition of polyolefin elastomers has proved to be an approachable solution for low impact strength of PP, while it would also reduce the young modulus and tensile strength. That is why reinforcement would be applied to this combination to enhance the elastic modulus. The mechanical properties of the prepared composites were devised to train an artificial neural network to predict these properties of the system in 6256 unknown points. Therefore, the sensitivity analysis was performed and the share of each input parameters on the respective output values was calculated. Additionally, a novel parameter called Nanocomposite Evaluation Criterion (NEC) is introduced to analyze the suitability of the nanocomposites considering the mechanical properties. Accordingly, the formulation with optimal mechanical properties of toughness, elongation break, tensile strength, Young modulus, and impact strength was obtained.
Structures and Properties of Polyimide with Different Pre-imidization Degrees
Fuyao Hao, Jianhua Wang, Shengli Qi, Guofeng Tian, Dezhen Wu
Accepted Manuscript , doi: 10.1007/s10118-020-2407-9
[Abstract](49) [PDF 1666KB](8)
A series of polyimide (PI) films derived from pyromellitic dianhydride (PMDA) and 4,4- oxydianiline (ODA) were prepared with the employment of chemical pre-imidization, and the pre-imidization degree (pre-ID) was found influential on structures and properties of the films obtained. Specifically, a certain degree of chemical imidization could promote the in-plane orientation of molecular chains inside the film, which then enhanced the mechanical strength and reduced the coefficient of thermal expansion (CTE) of the films. Further, such pre-imidization process could expand the internal space gap inside the films, thereby lowering their dielectric constant and glass transition temperature. Our study provides a new approach for preparing high-performance PI films through chemical imidization.
Rational design of conjugated polymers for d-limonene processed all-polymer solar cells with small energy loss
Meijing Li, Baobing Fan, Wenkai Zhong, Zhaomiyi Zeng, Jingkun Xu, Lei Ying
Accepted Manuscript , doi: 10.1007/s10118-020-2429-3
[Abstract](39) [PDF 681KB](12)
In this manuscript, we designed and synthesized a novel naphthalenediimide-based n-type conjugated polymer PNDICl, which bears asymmetric backbone containing a 3-chlorothiophene unit. The asymmetric structure associated with steric effects of the chlorine atom impart remarkable solubility of PNDICl in various organic solvents, enabling the fabrication of all-polymer solar cells (all-PSCs) by using an environmentally friendly solvent of d-limonene. Combined with a novel pyrrolo[3,4-f]benzotriazole-5,7(6H)-dione based p-type conjugated polymer P2F-Si with deep highest occupied molecular orbital energy level, the resulting d-limonene-processed all-PSCs presents an impressively high open-circuit voltage of approaching 1.0 V, corresponding to a very small energy loss of 0.49 eV. Through further morphology optimization by using γ-valerolactone, we demonstrated an impressive device efficiency of 4.2%, which is among the best photovoltaic performance of devices processed using d-limonene and comparable to that processed by conventional solvent, suggesting the great promise of using greener solvent for fabricating high-performance all-PSCs.
Thermostable α-diimine nickel complexes with substituents on acenaphthequinone-backbone for ethylene polymerization
Rui-Fang Zhang, Yan-Hui Hou, Xu-Ling Wei, Ding-Ding Zhao, Mi-Mi Cui, Fei-Fan Zhai Xiang-Liu Li, Bin-Yuan Liu, Min Yang
Accepted Manuscript , doi: 10.1007/s10118-020-2430-x
[Abstract](16) [PDF 688KB](1)
In order to promoting thermostability of α-diimine nickel complex by ligand backbone structure, a series of α-diimine nickel complexes with substituents on acenaphthequinone backbone were synthesized and used as catalysts for ethylene polymerization. When the hydroxyethyl phenoxyl group was introduced to the acenaphthequinone-backbone, the thermal stability and activity of the catalyst could be significantly improved. The catalytic activity of complex C2 [5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-diisopropyl)acenaphthylene- 1,2-diimine]nickel(II) dibromide with isopropyl substituents on N-aryl reached 8.2106 g/molNi·h at 70 °C and 2MPa. The activity of [5-(4-(2-hydroxyethyl)phenoxyl)-N,N-bis(2,6-dibenzhydryl-4-menthylphenyl)acenaphthylene-1,2-diimine]nickel(II) dibromide (C3) still maintained at 6.7105 g/molNi·h at 120 °C. Compared with C3 containing bulky dibenzhydryl substituents, the activity of C2 was sensitive to the change of the polymerization pressure. However, the polyethylenes obtained from complex C3 had lower branching density. Meanwhile, the molecular weight could reach 971 Kg/mol, which is almost 5 times as much as that of the polyethylene obtained from complex C2.
Differences in crystallization behaviors between cyclic and linear polymer nanocomposites
Rongjuan Liu, Zhiping Zhou, Yong Liu, Zhaopeng Liang, Yongqiang Ming, Tongfan Hao, Yijing Nie
Accepted Manuscript , doi: 10.1007/s10118-020-2403-0
[Abstract](53) [PDF 1770KB](6)
Cyclic polymers exhibit fascinating crystallization behaviors owing to the absence of chain ends and more compact conformations. In the current simulation, dynamic Monte Carlo simulations were performed to reveal the underlying mechanism of the effect of chain topology and chain length on crystallization of polymer solutions containing one-dimensional nanofiller. Simulation results suggested that the filled cyclic polymers exhibit higher melting temperature, higher crystallization temperature and faster crystallization rate than the analogous linear polymers of identical chain length, especially in the systems with relatively shorter chains. Based on the Thomson-Gibbs Equation, we theoretically analyzed the difference in the melting point between the cyclic and linear polymers under different chain lengths, and derived the dependence of the ratio of the melting point of the linear polymers to that of its cyclic analogs on chain length. In addition, it was also observed that the nanofiller can induce the formation of nanohybrid shish-kebab structure during isothermal crystallization of all systems.
Better choice: linear long chains rather than branched ones to improve mechanical performance of polyethylene through generating shish-kebabs
Lufeng Deng, Xi-Xi Zhang, Dong Zhou, Jian-Hua Tang, Jun Lei, Jun-Fang Li and Zhong-Ming Li
Accepted Manuscript , doi: 10.1007/s10118-020-2397-7
[Abstract](59) [PDF 7855KB](2)
We utilized two structurally different long chains (linear and branched ultra-high molecular weight polyethylene) to reveal the dependence of flow-induced crystallization on long chain architecture, and prepared two bi-disperse systems of 98 wt% short chain and 2 wt% long chain. A flow field was applied to the bi-disperse polyethylene melt by a modified injection-molding machine, known as oscillation shear injection molding (OSIM). For the first time, the structural influence of long chains on flow-induced shish-kebab formation was systematically investigated. For the intermediate layer of OSIM samples, the branched long chains are better than the linear long chains at inducing shish-kebab formation, agreeing with the reported literatures, because the branches can maintain their oriented conformations longer. But unexpectedly, the reverse is the case for the core layer of OSIM samples, where the shear flow is much weaker than the intermediate layer. To understand the unexpected phenomenon, the lifetime of shishes induced by different long chains has been compared. Result demonstrates that the linear-induced shishes possessed higher thermal stability than the branched-induced ones so that the linear-induced shishes can survive in the core layer of OSIM samples. Additionally, unlike other methods for flow-induced crystallization, OSIM could create samples for measuring mechanical properties, and thus offer the chance to reveal the relationship between structure and performance. The mechanical results demonstrate that both long chains remarkably enhanced the mechanical properties because of the significant promoting effect of long chains and intense flow fields on shish-kebab formation. However, the linear long chains induced more stable and flawless shishes with higher tensile strength and modulus (80.4 and 1613.5 MPa, respectively) than the branched ones (74.4 and 1489.3 MPa). Our research not only helps elucidate the mechanism of shish-kebab formation but also provides a better choice to reinforce polymers by adding long chains with suitable structure.
Nanofiltration Membranes via Layer-by-layer Assembly and Cross-linking of Polyethyleneimine/Sodium Lignosulfonate for Heavy Metal Removal
Meng-Yun Xie, Jiang Wang, Qing-Yun Wu
Accepted Manuscript , doi: 10.1007/s10118-020-2422-x
[Abstract](26) [PDF 1915KB](1)
Layer-by-layer (LbL) assembly technology is a facile method to construct thin film composite membrane. Herein, a novel nanofiltration (NF) membrane was prepared by LbL assembly of polyethyleneimine (PEI) and sodium lignosulfonate (LS) followed by cross-linking. The surface composition, morphology and property of PEI/LS bilayer were detailedly investigated by FTIR/ATR, XPS, SEM, AFM, and water contact angle test. The PEI/LS bilayer full of amino and hydroxyl groups presents increased roughness, and improved hydrophilicity. Moreover, the NF performance of PEI/LS LbL assembly membranes can be modulated by bilayer number, polyelectrolyte concentration and salt content. The water flux reduced while the salt rejection greatly improved as increasing the bilayer numbers, PEI concentration, or NaCl content. More than 95% MgSO4 and MgCl2, as well as 80% NaCl can be rejected by a NF membrane prepared by 6 PEI/LS bilayers, 1 wt% PEI, 0.5 wt% LS and 1 M NaCl. Furthermore, this NF membrane can be used to remove more than 95% heavy metal ions (Cd2+, Zn2+, Mn2+, Cr2+, Cu2+ and Ni2+). This work proposed a promising NF membrane by using PEI/LS as low cost polyelectrolytes and facile LbL assembly method, which should receive much attention in water purification.
Mechanism-Inspired Design of Heterodinuclear Catalysts for Copolymerization of Epoxide and Lactone
Wei-Min Ren, Rui-Jing Wang, Bai-Hao Ren, Ge-Ge Gu, and Tian-Jun Yue
Accepted Manuscript , doi: 10.1007/s10118-020-2413-y
[Abstract](55) [PDF 0KB](5)
Polyesters, as a class of high-performance and versatile polymer materials, often suffer from the drawbacks, such as hydrophobic and brittle due to their single structure nature. Thus, modifications have attracted much attention for enhanciing their desirable properties, of which one efficient way is incorporating the aliphatic polyether segment into the main chain of the polyester. However, this approach is of much challenge because that obtained polyesters are problematic in either low alternating degree or low molecular weight. Herein, we describe an efficient strategy to incorporate polyether fragment into polyester by developing a novel Co-Al based heterodinuclear complex for mediating the copolymerization of propylene oxide (PO) with ε-caprolactone (CL). The intermittent experiments reveal that PO and CL convert into the polymer chain throughout the polymerization process. Especially, the linear increase in the molecular weight with conversion of CL indicates the controllable nature of the copolymerization. The competition polymerization, offering the monomer reactivity ratios of rCL = 0.96, rPO = 1.04, suggest that the tendency of self-propagation or incorporation of monomers was nearly identical. Interestingly, the obtained polymers with different ether content exhibit the tunable thermal properties with the enhanced decomposition temperature of the polymer with higher ether content. The newly developed heterodinuclear complex for new polymerization provides an idea to synthesize new functional polymeric materials.
Wide Band-gap Two-Dimension Conjugated Polymer Donors with Different Amount Chlorine Substitution on Alkoxyphenyl Conjugated Side Chains for Non-Fullerene Polymer Solar Cells
Youdi Zhang, Yong Wang, Ruijie Ma, Zhenghui Luo, Tao Liu, So-Huei Kang, He Yan, Zhongyi Yuan, Changduk Yang, Yiwang Chen
Accepted Manuscript , doi: 10.1007/s10118-020-2435-5
[Abstract](18) [PDF 1755KB](2)
In this study, wide bandgap (WBG) two-dimensional (2D) copolymer donors (DZ1, DZ2 and DZ3) based on benzodithiophene (BDT) on alkoxyphenyl conjugated side chains without and with different amount chlorine atoms and difluorobenzotriazole (FBTZ) is designed and synthesized successfully for efficient non-fullerene polymer solar cells (PSCs). Three polymer donors DZ1, DZ2 and DZ3 display similar absorption spectra at 300-700 nm range with optional band-gap (Egopt) of 1.84, 1.92 and 1.97 eV, respectively. Compared with reported DZ1 without chlorine substitution, it is found that introducing chlorine atoms into the meta-position of the alkoxyphenyl group led to polymer possessing a deeper the highest occupied molecular orbital (HOMO) energy level, which can increase open circuit voltage (VOC) of PSCs, as well as improve hole mobility. Non-fullerene bulk heterojunction PSCs based on DZ2:MeIC demonstrate a relatively high power conversion efficiency (PCE) of 10.22% with a VOC of 0.88 V, a short-circuit current density (JSC) of 17.62 mA/cm2, and a fill factor (FF) of 68%, compared with PSCs based on DZ1:MeIC (a PCE of 8.26%) and DZ3:MeIC (a PCE of 6.28%).The results imply that adjusting chlorine atom amount on alkoxyphenyl side chains based on BDT polymer donors is a promising candidate as an electron-rich building block for high performance of PSCs.
Antistatic Structural Color and Photoluminescent Membranes from Co-Assembling Cellulose Nanocrystals and Carbon Nanomaterials for Anti-counterfeiting
Si-Yuan Liu, Yan-Bin Gong, Shan Ma, Yu-Huan Wang, Lin Gan, and Jin Huang
Accepted Manuscript , doi: 10.1007/s10118-020-2414-x
[Abstract](36) [PDF 1403KB](8)
Static charges on optical anti-counterfeiting membranes may lead to materials structural changes, dust stain aggravation, and optical information. Incorporating conductive particles is a common way to transfer accumulative charges, but the key issue is how to achieve highly dispersion and effective distribution of particles. According to the strategy of assembly-induced structural colors, cellulose nanocrystals (CNCs) were employed as a solid emulsifier to stabilize hydrophobic carbon nanoparticles (CNPs) in aqueous media; subsequently, by solvent-evaporation-modulated co-assembly under a condition of 30 C and 20 RH%, the binary suspensions containing 2 wt% CNC and CNPs, which concentration equivalent relative to CNC ranged from 1:40 to 1:10, were used to prepare antistatic composite membranes. Surface chemistry regulation of CNCs was applied to optimize the dispersibility of CNPs and the orientation of assembled CNC arrays, and the hydrophilic CNCs were more favorable for dispersion and assembly of binary suspension systems. Meanwhile, one-dimension carbon nanotube (CNT) and zero-dimension carbon black (CB) were found to show better dispersibility than two-dimension graphene, which was verified by a semi-quantitative theoretical study. Moreover, the stable binary systems of CNT/CNC and CB/CNC were chosen for co-assembly as membranes, and the uniaxial orientation could be optimized as the full-width of 9.8 at half-maximum deviation angle while the surface resistivity could also drop down to 3.42×102 Ω∙cm∙cm-1. The structural color character of such paper-homology and antistatic-integrated membranes contributes to optical information hiding-and-reading, and shows great potential as optical mark recognition materials for electrostatic discharge protective packaging and anti-counterfeiting applications.
Polyphosphoester-Modified Cellulose Nanocrystals for Stabilizing Pickering Emulsion Polymerization of Styrene
Kun-Ming Che, Ming-Zu Zhang, Jin-Lin He, Pei-Hong Ni
Accepted Manuscript , doi: 10.1007/s10118-020-2404-z
[Abstract](58) [PDF 2009KB](16)
The structure and properties of functional nanoparticles are important for stabilizing Pickering emulsion polymerization. Recently, cellulose nanocrystals (CNCs) are increasingly favored as a bio-based stabilizer for Pickering emulsions. In this study, we reported a novel functionalized polyphosphoester-grafted CNCs for the stabilization of oil-in-water Pickering emulsions and the emulsion polymerization of styrene. First, polyphosphoester containing an amino at one end of the chain, abbreviated as PBYP-NH2, was prepared by ring-opening polymerization (ROP) and hydrolysis reaction, wherein PBYP represents poly[2-(but-3-yn-1-yloxy)-2-oxo-1,3,2- dioxaphospholane]. Subsequently, CNC-COOH was obtained via 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation of CNCs. The functionalized nanocrystals CNC-PBYP-COOH with carboxyl groups and polyphosphoester on the surface were obtained by the reaction of PBYP-NH2 with CNC-COOH. Finally, we used CNC-PBYP-COOH as sole particle emulsifiers to stabilize styrene-in-water Pickering emulsions and studied its effects on the emulsions in details by using dynamic light scattering (DLS). The results indicated that the properties of these emulsions depended on the concentration of hydrophobically modified CNCs, volume ratios of oil to water and pH values. The modified CNCs had higher ability to stabilize the styrene-in-water emulsions relatived to the unmodified CNCs, and a stable oil-in-water (o/w) Pickering emulsion with diameter of hundreds of nanometers could be obtained. The resulting emulsions could be polymerized to yield nanosized latexes. The polyphosphoester-modified CNCs as green particle emulsifiers can efficiently stabilize nanoemulsions and latexes, which would promote the development of novel environmentally friendly materials.
Long-term thermo-oxidative degradation modeling of a carbon fiber reinforced polyimide composite: Multistep degradation behaviors and kinetics
Yi Liu, Xiaozhou Xu, Song Mo, Bangwei Lan, Caizhen Zhu, Cuihua Li, Jian Xu, Lin Fan
Accepted Manuscript , doi: 10.1007/s10118-020-2425-7
[Abstract](65) [PDF 1813KB](2)
This study aims to disclose the thermo-oxidative degradation behaviors and kinetics of a carbon fiber reinforced polyimide (CFRPI) composite for modeling of the long-term degradation process. The degradation behaviors were revealed through off-gas products analysis, and the overall kinetic interpretation was achieved from study of the mass-loss curves recorded under dynamic conditions. It was found that thermo-oxidative degradation of the CFRPI composite was a multistep process, which included four main reaction steps. Since most kinetic analysis methods were derived from simple reactions described by a single kinetic triplet, they cannot be applied reliably to such a process. Therefore, we firstly separated the four overlapped reaction steps by peak fitting of derivative thermogravimetric curves using Frasier-Suzuki equation considering the asymmetrical nature of kinetic curves, and subsequently analyzed each individual reaction employing Friedman method and experimental master-plots method. Four sets of kinetic triplets were determined to characterize the entire degradation process. The validity of four corresponding kinetic triplets was confirmed by perfect simulation of mass-loss curves recorded at both dynamic conditions used in kinetic analysis and entirely different isothermal conditions. Finally, modeling of long-term aging at 400 oC of the CFRPI composite was successfully achieved based on these kinetic triplets. The predicted mass loss and flexural property correlated well with experimental results. This study can serve as a basis for rapid evaluation of the long-term durability of the CFRPI composite in various application environments.
Revisiting Silica Networks by Small-Angle Neutron Scattering and Synchrotron Radiation X-ray Imaging Techniques
Xin-Wei Kang, Dong Liu, Ping Zhang, Ming Kang, Feng Chen, Qing-Xi Yuan, Xiu-Li Zhao, Ying-Ze Song, and Li-Xian Song
Accepted Manuscript , doi: 10.1007/s10118-020-2402-1
[Abstract](118) [PDF 1786KB](10)
The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler structure of silica. Nevertheless, the filler network structure and corresponding reinforcement mechanism are still under debate and need to be further probed with the aid of applicative advanced analysis techniques. Herein, small-angle neutron scattering (SANS) and synchrotron radiation X-ray nano-computed tomography (Nano-CT) techniques are employed to explore the evolution of filler networks of fumed, precipitated and sol-gel silica, respectively. Our studying results reveal the formation of filler network constructed by the interconnecting of branched silica aggregates. And the silica with high structure, pertaining to amorphous morphology, small size and large surface area presents short distance and effective molecular chain bridge between aggregates, thus forming strong and steady filler networks. This work would provide deep-seated revisiting of filler networks and corresponding reinforcement mechanism and offer guidance for optimizing the mechanical properties of silicone rubber.
Facile Construction of Synergistic β-Glucosidase and Cellulase Sequential Co-immobilization System for Enhanced Biomass Conversion
Guan Wang, Kai Zhang, Jiayi Xin, Changwen Zhao, Yuhong Ma, and Wantai Yang
Accepted Manuscript , doi: 10.1007/s10118-020-2437-3
[Abstract](13) [PDF 1503KB](1)
Converting renewable cellulose into glucose via cellulase catalysis for further production of biofuel has been recognized as one of the most promising way to solve energy crisis. However, the hydrolysis performance of immobilized cellulase was not satisfied for practical application due to the reduced catalytic efficiency and lack of β-glucosidase (BG) component in cellulase. Here a facile method was developed to sequentially co-immobilize BG and cellulase by polymeric microparticles with hierarchical structure. In this strategy, BG was firstly entrapped into the cross-linked poly(ethylene glycol) (PEG) microparticles via inverse emulsion polymerization initiated by isopropyl thioxanthone (ITX) under the irradiation of visible light, left the formed ITX semi-pinacol (ITXSP) dormant groups on surface of BG-loaded microparticles, which could be further activated by visible light irradiation and initiated a graft polymerization to introduce poly(acrylic acid) (PAA) brush on the PEG core. After that, cellulase was covalently bonded on the PAA chains via carbodiimide reaction. The synergic effect of BG and cellulase was verified in the dual enzyme immobilization system, and it showed a better stability at a wide range of temperature and pH than free enzymes. The dual enzymes system exhibited excellent reusability, which could retain 75% and 57% of the initial activity after 10 cycles hydrolysis of carboxyl methyl cellulose and 5 cycles hydrolysis of filter paper, respectively, indicated of the potential in biofuel areas in a cost-effective manner.
Synthesis of Functional Hyperbranched Poly(methyltriazolylcarboxylate)s by Catalyst-Free Click Polymerization of Butynoates and Azides
Muning Lang, Weiwen Chi, Ting Han, Qingzhen Zhao, Hongkun Li, Ben Zhong Tang, and Yongfang Li
Accepted Manuscript , doi: 10.1007/s10118-020-2421-y
[Abstract](27) [PDF 1349KB](3)
Azide–alkyne click polymerization has become a powerful tool for polymer synthesis. However, the click polymerization between internal alkynes and azides is rarely utilized to prepare functional polymers. In this work, the polymerization reactions of activated internal alkyne monomers of tris(2-butynoate)s (1) with tetraphenylethene-containing diazides (2) were performed in dimethylformamide (DMF) under simple heating, affording four hyperbranched poly(methyltriazolylcarboxylate)s (hb-PMTCs) with high molecular weights (Mw up to 24 000) and regioregularities (up to 83.9%) in good yields. The hb-PMTCs are soluble in common organic solvents, and thermally stable with 5% weight loss temperatures up to 400 °C. They are non-emissive in dilute solution, but become highly emissive in aggregated state, exhibiting aggregation-induced emission characteristics. The polymers can generate fluorescent photopatterns with high resolution, and can work as fluorescent sensors to detect nitroaromatic explosive with high sensitivity.
Enhancement of β-phase Crystal Content of Poly(vinylidene fluoride) Nanofiber Web by Graphene and Electrospinning Parameters
Lu Jin, Yan Zheng, Zekun Liu, Jiashen Li, Yangpeiqi Yi, Yangyang Fan, Lulu Xu, and Yi Li
Accepted Manuscript , doi: 10.1007/s10118-020-2428-4
[Abstract](24) [PDF 1533KB](1)
Electrospun poly(vinylidene fluoride) (PVDF) nanofiber web has been widely utilized as a functional material in various flexible sensors and generators due to its high piezoelectricity, ease processability and low cost. Among all the crystalline phases of PVDF, β-phase is a key property for PVDF nanofiber web, because the content of β-phase is directly proportional to piezoelectric performance of PVDF nanofiber web. Herein, the impact of graphene content (GC), tip-to-collector distance (TCD) and rotational speed of collector (RSC) as well as their interactions on the β-phase formation of PVDF nanofiber web is systematically investigated via design of experimental method. The fraction of each crystalline phase of PVDF nanofiber web is calculated by FTIR spectra, and the crystallinity is determined by XRD patterns. The influence of GC, TCD and RSC on both β-phase fraction and crystallinity of PVDF nanofiber are analyzed using Minitab program. The results show that all GC, TCD and RSC have significant effect on the β-phase content of PVDF nanofiber web, and GC is the most significant one. In addition, an optimal electrospinning condition (GC=1 wt.%, TCD=4 cm and RSC=2000 rpm) to fabricate high β-phase crystallinity of PVDF nanofiber web is drawn, the crystallinity can reach 41.7 %. The contributions in this study could provide guidance for future research on fabricating high performance PVDF nanofiber web based sensors or generators.
Characterizations and photothermal properties of narrow bandgap conjugated polymer nanoparticles
Yu-Lin Zhang, Jun-Tao Ren, Huai-Yu Gao, Jia-Wei Liu, Wen-Jie Xia, Wen-Qiang Qiao, and Zhi-Yuan Wang
Accepted Manuscript , doi: 10.1007/s10118-020-2420-z
[Abstract](27) [PDF 1318KB](4)
Photothermal therapy (PTT) is a minimally invasive treatment that kills cancer cells by converting photon energy into heat. The past few decades have witnessed the booming development of photothermal materials, mainly focusing on precious metal nanomaterials and carbon nanomaterials, such as nanogold and silver and nanocarbon materials for near-infrared (NIR) light-triggered PTT. As precious metals are expensive and potentially harmful to humans, exploration and development of a new type of photothermal materials has become a research hotspot in this field. Herein, we report narrow bandgap conjugated polymer nanoparticles (PDPP NPs) based on pyrrolo [3,4-c] pyrrole-1,4-dione (DPP) with intense NIR absorption at 900 nm, as well as a photothermal energy conversion efficiency of 75%. This polymer nanoparticle is essentially non-toxic, as the cell viability of mouse remained more than 90%, even when the concentration of PDPP NPs was at 0.5 mg·mL-1
A synchrotron in-situ X-ray study on the multiple melting behaviors of isomorphous Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with middle HV content
Hao Zhu, You Lv, Dan Shi, Yiguo Li, Weijun Miao and Zongbao Wang
Accepted Manuscript , doi: 10.1007/s10118-020-2427-5
[Abstract](21) [PDF 2731KB](3)
The multiple endothermic peaks without observable recrystallization phenomenon of isomorphous poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB-co-HV)] with the middle HV content of 19.4 and 28.7 mol% were confirmed by differential scanning calorimetry (DSC), and the evolutions of crystal structure and lamellar morphology during the heating and melting process were followed by in-situ synchrotron wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) techniques. The emergence of asymmetric features of both the diffraction peaks and scattering curves indicates the coexistence of different lamellar crystals with varied unit cell parameters. Based on the in-situ WAXD and SAXS measurements, we calculated the evolutions of the unit cell parameters a and b as well as the long period and lamellar thickness upon heating. The comparative analysis of WAXD and SAXS data confirms that the multiple endothermic peaks of P(HB-co-19.4%HV) and P(HB-co-28.7%HV) are resulted from the melting of different lamellae rather than the melting/recrystallization. The thinner, unstable uniform lamellae with HV counits total inclusion melt first and the thicker, stable sandwich lamellae with HV counits partial inclusion melt last. In addition, the large second melting peak in P(HB-co-19.4%HV), differing to that of samples with HV content of 28.7 and 36.2 mol%, is due to the unique state of HV content leading to a transition of sandwich lamellae to uniform lamellae. The present study establishes the relationship between the different lamellae structure and multiple melting behaviors of isomorphous copolymer.
Soluble Polyimide-reinforced TGDDM and DGEBA Epoxy Composites
Qi Chen, Shun Wang, Feng Qin, Kuan Liu, Qian Liu, Qing Zhao, Xingyi Wang, and Yanhong Hu
Accepted Manuscript , doi: 10.1007/s10118-020-2395-9
[Abstract](86) [PDF 1802KB](0)
Polyimide (PI) synthesized from aromatic diamine and dianhydrides via two-step poly-condensation method was highly soluble in TGDDM (MY-720) and DGEBA (E-51) at desirable temperature. TGDDM-PI (M-PI) and DGEBA-PI (E-PI) composites within 0.5 ~ 3% PI loading could be prepared without organic solvent. On the cryogenically fractured surfaces of M-PI and E-PI composites, no obvious heterogeneous phase was observed by SEM. The mechanical properties were promoted significantly by PI, especially for impact strength. Adding 2% PI-2W into MY-720 and E-51 composites, the impact strength increases to 21 and 51 kJ/m2; the tensile strength increases by 62% and 19%, and the flexural strength, 18% and 13%, with slight increases in tensile modulus. These results were related to the promotion in plasticity of composites and changes in fragile→ductile fracture mode. Moreover, Tg and thermal stability of M-PI and E-PI were increased effectively.
PEN/BADCy Interlayer Dielectric Films with Tunable Microstructures via an Assist of Temperature for Enhanced Frequency Stability
Xi-Ting Lei, Li-Fen Tong, Ming-Zhen Xu, Yong You, and Xiao-Bo Liu
Accepted Manuscript , doi: 10.1007/s10118-020-2417-7
[Abstract](32) [PDF 1742KB](6)
Low dielectric interlayer films have become an important element to ensure the development of the microelectronics industry. A kind of flexible interlayer dielectrics, polyarylene ether nitrile/ bisphenol A cyanate ester (PEN/BADCy) film, with good thermal stability and low frequency dependence, have been developed by solution casting method. Herein, materials were designed to incorporate bisphenol A cyanate ester as a part of blend, contributing to the frequency stability and structural integrity. The morphological study combined with electron microscopy revealed the uniform and flexible microstructure information with controllable morphology through self-polymerization of cyanate esters with different prepolymerization time and curing temperature. The dielectric films can present high thermal stability with Tg > 180 oC. Significant improvement in the dielectric properties was achieved for the dielectric constant and loss was much stable than pure PEN over the frequency range from 100 Hz to 5 MHz. When the prepolymerization time is 3 h and final curing temperature reaches 230 oC, the dielectric constant and dielectric loss of the films are 3.36 and 0.013 at 100 kHz, respectively. The dimensional stability (CTE = 53.67 ×10^(-6) K-1) is confirmed and considered beneficial for use as an interlayer dielectrics.
Mechanical Properties, Crystallization and Biodegradation Behavior of the Polylactide/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/Poly(butylene adipate-co-terephthalate) Blown Films
Xiangyu Wang, Hongwei Pan, Shiling Jia, Zengwen Cao, Lijing Han, Huiliang Zhang, Lisong Dong
Accepted Manuscript , doi: 10.1007/s10118-020-2418-6
[Abstract](21) [PDF 2607KB](0)
Polylactide (PLA), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) P(3HB-co-4HB) and poly(butylene adipate-co-terephthalate) (PBAT) ternary blends were prepared by extrusion blending. The biodegradable PLA/P(3HB-co-4HB)/PBAT films were successfully obtained by using blown films technique. Excellent stiffness-toughness balance was achieved for 55/10/35 PLA/P(3HB-co-4HB)/PBAT film. The tensile strength reached 33.0 MPa (MD) and 23.5 MPa (TD), the elongation at break exceeded 130 % and tear strength exceeded 110 kN/m. The Young's modulus as low as about 1800 MPa also met packaging applications. From SEM analysis, it exhibited that rough and long ligaments, indicating that the tear specimens were broken yieldingly. The addition of PBAT elastomers is the main reason for improving the toughness of the film. From DMA and SEM analysis, it demonstrated that the PLA, P(3HB-co-4HB), and PBAT had partially compatibility. With increasing P(3HB-co-4HB) content, the melt and cold crystallization of PLA was promoted. The enzymatic degradation experiments indicated that the films had good biodegradability. These findings gave important implications for designing and manufacturing biodegradation package of high biological carbon content.
Investigation on self-healing property of epoxy resins based on disulfide dynamic links
Zijian Li, Jiang Zhong, Maochen Liu, Jinchuang Rong, Kun Yang, Jiyong Zhou, Liang Shen, Fei Gao, Haifeng He
Accepted Manuscript , doi: 10.1007/s10118-020-2406-x
[Abstract](67) [PDF 1556KB](5)
Self-healing polymers based on dynamic crosslinkers have drawn rapidly increasing interest over the last decade. Here, a self-healable epoxy network with exchangeable disulfide bonds was synthesized by polymerizing two epoxies with an aromatic amine containing a disulfide bond. The bisphenol a diglycidyl ether (DGEBA) and poly (ethylene glycol) diglycidyl ether (DER736) were used as rigid and soft components, respectively. The crosslink densities of studied polymers decreased with the increasing amount of DER736, resulting in the lower glassy temperature and weaker mechanical strength. The dynamic covalent network character of disulfide bond and its low active energy were also investigated through stress relaxation experiments at various temperatures. The self-healing performance of healable epoxy resins with varied flexibility was measured by tensile tests. The tensile strength of a full-cut sample was restored to 84 % (13 MPa) of the initial values (16 MPa) at moderate temperature. Its healed fracture strain was up to 505 %. Moreover, the effect of healing time and temperature on the self-healing properties was also studied. A model was proposed to investigate the self-repairing efficiency evolution with healing time, suggesting that hydrogen bonds mainly contributed to the initial sticking or interfacial adhesion, the disulfide links and chain interdiffusion assisted time dependent reformation of networks to restore the original mechanical strength.
Accelerated aging behaviors and mechanism of fluoroelastomer in lubricating oil medium
Qi-long Wang, Jing-ke Pei, Gao Li, Xi He, Yan-hua Niu, Guang-xian Li
Accepted Manuscript , doi: 10.1007/s10118-020-2410-1
[Abstract](43) [PDF 3817KB](4)
The aging behaviors and mechanism of fluoroelastomer (FKM) under lubricating oil (FKM-O) and air (FKM-A, as a comparison) at elevated temperatures were studied from both the physical and chemical viewpoints. The obvious changes of mechanical and swelling performances indicate that the coupling effect of lubricating oil and temperature causes more serious deterioration of FKM-O compared to that of FKM-A. Meanwhile, much stronger temperature dependence of both bulk properties and micro-structures for FKM-O is found. Three-stage physical diffusion process is defined in FKM-O due to the competition between oil diffusion and elastic retraction of network. FTIR results reveal that the dehydrofluorination reaction causes the fracture of C-F bonds and produces a large number of C=C bonds in the backbone. The coupling effect of oil medium and high temperature could accelerate the scission of C=C bonds and generate a series of fragments with different molecular size. The TGA results, crosslinking density Ve and glass transition temperature Tg derived from different measurements coherently demonstrate the network destruction in initial stage and the simultaneous reconstruction occurring at the final stage. The newly formed local network induced by reconstruction cannot compensate the breaking of the original rubber network thus only provides lower tensile strength and thermal stability.
Preparation of Degradable Polymenthide and its Elastomers from Biobased Menthide via Organocatalyzed Ring-opening Polymerization and UV Curing
Na Zhao, Xinxin Cao, Jinfeng Shi, Zhibo Li
Accepted Manuscript , doi: 10.1007/s10118-020-2415-9
[Abstract](37) [PDF 1038KB](7)
Development of degradable polyester elastomers plays an important role in the applications of soft mateirals. Noncrystalline polymenthides (PMs) from menthol derived lactone monomers are excellent soft segments for preparing degradable polyester elastomers. By using cyclic trimeric phosphazene base (CTPB) as organocatalyst, we successfully synthesized PMs with different molecular weights (8.2 to 100.7 kDa) in high yields via ring-opening polymerization (ROP) of menthide. When a CTPB/urea binary catalytic system was adopted, the polymerizations proceed in a more controlled manner. Using glycerol as initiator, star shaped PMs with well-defined structure were synthesized and subsequently end-capped by acrylate. UV irradiation of the terminal acrylate groups in the star-shaped PMs resulted in formation of chemically cross-linked polyester elastomers without heat or other stimuli. The obtained polyester elastomers exhibit matched modulus (3.8-5.5 MPa), tensile strength (0.56-0.68 MPa), and strain at break (280-320 %) with soft body tissues, displaying great potential in biomedical applications.
Phase Separation in PCDTBT:PCBM Blends: from Flory–Huggins Interaction Parameters to Ternary Phase Diagrams
Monika Biernat, Paweł Dąbczyński, Paweł Biernat, Jakub Rysz
Accepted Manuscript , doi: 10.1007/s10118-020-2424-8
[Abstract](26) [PDF 5901KB](7)
The substantial increase in the efficiency of organic solar cells achieved in recent years would not have been possible without work on the synthesis of new materials and understanding the relationship between the morphology and performance of organic photovoltaic devices. The structure of solvent-cast active layers is a result of phase separation in mixtures of donor and acceptor components. To a large extent, this process depends on the interactions between the components of the mixture. Here, we present a systematic analysis of the morphology of poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’-enzothiadiazole)] (PCDTBT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) films in terms of the ternary phase diagram. The interaction parameters between PCDTBT and four different solvents, namely chloroform, chlorobenzene, o-dichlorobenzene and toluene, were estimated based on swelling experiments. Based on these values, ternary phase diagrams of PCDTBT:PC70BM in different solvents were calculated. The morphology of spin-coated films with different blend ratios cast from different solvents is discussed in terms of the obtained phase diagrams.
Sustainable blends of poly (propylene carbonate) and stereocomplex polylactide with enhanced rheological properties and heat resistance
Yi Li, Yan-Cun Yu, Chang-Yu Han, Xian-Hong Wang and De-Xin Huang
Accepted Manuscript , doi: 10.1007/s10118-020-2408-8
[Abstract](48) [PDF 926KB](8)
Sustainable blends of poly (propylene carbonate) (PPC) and stereocomplex polylactide (sc-PLA) were prepared by melt blending equimolar poly(L-lactic acid) (PLLA) and poly(D-lactide acid) (PDLA) with PPC to form sc-PLA crystals in situ during melt blending process. Differential scanning calorimetry analysis revealed that only sc-PLA, no homo-crystallization of PLLA or PDLA formed in the PPC matrix as the sc-PLA content was more than 10 wt%. Very intriguingly, scanning electronic microscopy observation showed that sc-PLA was evenly dispersed in the PPC phase as spherical particles and the sizes of sc-PLA particles did not obviously increase with increasing sc-PLA content. As a consequence, the rheological properties of PPC were greatly improved by incorporation of sc-PLA. When the sc-PLA content was 20 wt%, a percolation network structure was formed, and the blends showed solid-like behavior. The sc-PLA particles could reinforce the PPC matrix, especially at a temperature above the glass transition temperature of PPC. Moreover, the vicat softening temperature of PPC/sc-PLA blends could be increased compared with that of pure PPC.
High Open-circuit Voltage and Low Voltage Loss in All-polymer Solar Cell with a Poly(coronenediimide-vinylene) Acceptor
Han Han, Fujin Bai, Rong Wei, Han Yu, Yikun Guo, He Yan and Dahui Zhao
Accepted Manuscript , doi: 10.1007/s10118-020-2426-6
[Abstract](30) [PDF 924KB](4)
Reducing the voltage loss (Vloss) is a critical factor in optimizing the open-circuit voltage (Voc) and overall power-conversion efficiency (PCE) of polymer solar cells. In the current work, by designing a novel electron-accepting unit of coronenediimide (CDI) and use it as the main functional building block, a new polymer acceptor CDI-V is developed and applied to fabricate all-polymer solar cells. Compared with the perylenediimide-based polymer acceptors we previously reported, the current CDI-V polymer possesses a noticeably elevated lowest unoccupied molecular orbital (LUMO). Thereby, by virtue of the enlarged energy gap between the donor HOMO and acceptor LUMO, a high Voc value of 1.05 V is achieved by the all-polymer photovolatic device, along with an impressively low Vloss of 0.55 V. As remarkably, in spite of an extremely small LUMO level offset of 0.01 eV exhibited by the donor and acceptor polymers, effective charge separation still takes place in the all-polymer device, as evidenced by a proper short-circuit current (Jsc) of 9.5 mA∙cm-2 and a decent PCE of 4.63%.
Effect of Olefin-Based Compatibilizers on the Formation of Cocontinuous Structure in Immiscible HDPE/iPP blends
Fei Yang, Li Pan, Huizhen Du, Zhe Ma, and Yuesheng Li
Accepted Manuscript , doi: 10.1007/s10118-020-2433-7
[Abstract](16) [PDF 5748KB](0)
In this work, the formation of cocontinuous structure in immiscible high density polyethylene/isotactic polypropylene (HDPE/iPP) blends was investigated for various olefin-based compatibilizers of distinct molecular architectures, including ternary random copolymer EPDM, olefin block copolymer (OBC), polypropylene-based OBC (PP-OBC), ethylene/-olefin copolymer (POE), bottlebrush polymer poly(1-dodecene), and comb-like poly(propylene-co-high -olefin) (PPO). The scanning electron microscope results show that after adding OBC, PP-OBC and POE copolymers, the finer droplet-in-matrix morphologies were obtained in 70/30 HDPE/iPP blend. Interestingly, for 70/30 HDPE/iPP blend with just 5 wt% of PPO copolymers, the phase inversion from droplet-in-matrix to cocontinuous morphology can be observed. It was proposed that the development of cocontinuous morphology contained the following steps: 1) interfacial saturation of compatibilizers and droplet deformation, 2) droplet-droplet coalescence, 3) continuity development, and 4) the formation of dual-phase continuity. Among the diverse copolymers studied in this work, PPO copolymer can be easily removed out of the interface during droplet coalescence and stabilize the curvature of minor fiber phase, facilitating the formation of cocontinuous morphology. In contrast, other olefin-based compatibilizers (EPDM, OBC, PP-OBC, POE) exhibit the distinct steric repulsion effect to prohibit from droplet coalescence. Moreover, the cocontinous interval varies with the compatibilizer architectures. Surprisingly, after adding 10 wt% of PPO copolymers, the cocontinuous interval was greatly broadened from HDPE/iPP range of 45/55 - 60/40 to that of 40/60 - 70/30.
Infusing high-density polyethylene with graphene-zinc oxide to produce antibacterial nanocomposites with improved properties
Youli Yao, Manuel Reyes De Guzman, Hong Duan, Chen Gao, Xu Lin, Yihua Wen, Juan Du, Li Lin, Jui-Chin Chen, Chin-San Wu, Maw-Cherng Suen, Yali Sun, Wei-Song Hung, and Chi-Hui Tsou
Accepted Manuscript , doi: 10.1007/s10118-020-2392-z
[Abstract](85) [PDF 2196KB](8)
Nanocomposites of high-density polyethylene (HDPE) modified with 0.2 phr graphene-zinc oxide (GN-ZnO) exhibited optimal mechanical properties and thermal stability. Two other nano-materials—GN and nano-ZnO—were also used to compare them with GN-ZnO. Increasing the content of GN-ZnO gradually enhanced the antibacterial and barrier properties, but the addition of 0.3 phr GN-ZnO led to agglomeration that caused defects in the nanocomposites. Herein, we investigated the antibacterial and barrier properties of HDPE nanocomposites infused with different nanoparticles (GN, ZnO, GN-ZnO) of varying concentrations. HDPE and the nanoparticles were melt-blended together in a Haake-Buchler Rheomixer to produce a new environment-friendly nano-material with improved physical and chemical properties. The following characterizations were conducted: tensile test, thermogravimetric analysis, morphology, differential scanning calorimetry, X-ray diffraction, antibacterial test, and oxygen and water vapor permeation test. The results showed that the crystallinity of HDPE was affected with the addition of GN-ZnO, and the nanocomposites had effective antibacterial capacity, strong mechanical properties, high thermal stability, and excellent barrier performance. This type of HDPE nanocomposites reinforced with GN-ZnO would be attractive for packaging industries.
COFs based Porous Material for Photocatalytic Applications
Xun-Liang Hu, He-Guo Li, Bi-En Tan
Accepted Manuscript , doi: 10.1007/s10118-020-2394-x
[Abstract](55) [PDF 1148KB](3)
Covalent organic frameworks(COFs) are an emerging class of photoactive material, solely composed of light elements. Owing to their ordered structure, crystallinity and high porosity led to enormous worldwide attention in many research fields. The extensive π-electron conjugation, light-harvesting and charge transport characteristics make them a fascinating polymer for photocatalytic systems. Versatile selection of building blocks and innumerable synthetic methodologies make it a robust platform for solar energy production. In this mini-review, we summarized recent progress and challenges of the design, construction, and applications of COFs-based photocatalysts, and also presented some perspectives on challenges.
Design and Properties of Fluoroelastomer Composites via Incorporation of MWCNTs with Varies Modification
Guangyao Yang, Lifen Tong, and Xiaobo Liu
Accepted Manuscript , doi: 10.1007/s10118-020-2405-y
[Abstract](49) [PDF 3333KB](6)
MWCNTs modified with silane coupling agent A-1120 (MWCNTs-A1120) were prepared. Compared with the raw MWCNTs, acidified MWCNTs (MWCNTs-COOH) and MWCNTs grafted with EDA (MWCNTs-NH2), MWCNTs-A1120 have the best dispersion in fluoroelastomer at the same doping ratio. Therefore, fluoroelastomer/MWCNTs-A1120 composite has the best mechanical properties with tensile strength of 13.92 MPa, elongation at break of 111.78%. Then, the effects of doping amount of MWCNTs-A1120 on the electrical properties of the composites were investigated. The dielectric constant of the composite increases with the increase of MWCNTs-A1120, and the dielectric loss does not change much. When the doping amount of the MWCNTs-A1120 is 5 wt%, the dielectric constant and the dielectric loss value are greatly increased, and the volume resistivity is greatly decreased, which proves that the conductive network is formed in the composite, so the filling amount of 5 wt% is the percolation threshold. The tensile deformation of the sample also affects the electrical properties of the composites. As the tensile deformation increases, the dielectric constant and dielectric loss of the composite decrease. For the composite with 5 wt% MWCNTs-A1120, excessive tensile deformation will destroy the conductive network structure of the composite, so the composite will change from conductive material to dielectric material. Therefore, such composite is a good candidate for flexible conductive material or flexible dielectric material used in harsh environments such as high temperatures and various aggressive solvents.
Supergiant Barocaloric Effects in Acetoxy Silicone Rubber over a Wide Temperature Range: Great Potential for Solid-state Cooling
William Imamura, Érik Oda Usuda, Lucas Soares Paixão, Nicolau Molina Bom, Angelo Marcio Gomes, Alexandre Magnus Gomes Carvalho
Accepted Manuscript , doi: 10.1007/s10118-020-2423-9
[Abstract](25) [PDF 1435KB](0)
Solid-state cooling based on caloric effects is considered a viable alternative to replace the conventional vapor-compression refrigeration systems. Regarding barocaloric materials, recent results show that elastomers are promising candidates for cooling applications around room-temperature. In the present paper, we report supergiant barocaloric effects observed in acetoxy silicone rubber – a very popular, low-cost and environmentally friendly elastomer. Huge values of adiabatic temperature change and reversible isothermal entropy change were obtained upon moderate applied pressures and relatively low strains. These huge barocaloric changes are associated both to the polymer chains rearrangements induced by confined compression and to the first-order structural transition. The results are comparable to the best barocaloric materials reported so far, opening encouraging prospects for the application of elastomers in near future solid-state cooling devices.
Increased Hydrogen-Bonding of Poly (m-phenylene isophthalamide) (PMIA) with Sulfonate Moiety for High-Performance Easily Dyeable Fiber
Na Li, Xingke Zhang, Junrong Yu, Yan Wang, Jing Zhu and Zuming Hu
Accepted Manuscript , doi: 10.1007/s10118-020-2416-8
[Abstract](28) [PDF 3062KB](5)
The demand for high thermal stability and high strength agents is growing steadily as a result of their increasing application in advanced materials. A series of sulfonated poly(m-phenyleneisophthalamide) (SPMIA) copolymers with superior thermal stability and good mechanical properties have been prepared via low temperature polycondensation method. Then the structures of SPMIA copolymers with different content quantities 2, 4-diaminobenzenesulfonic acid (2,4-DABSA) were confirmed by Fourier transform infrared (FTIR). Besides, their superior thermal properties were systematically investigated by Differential scanning calorimetry (DSC), Thermalgravimetreic analysis (TGA) and dynamic mechanical analysis (DMA). SPMIA fibers were obtained by wet spinning using the resulted SPMIA solutions. In addition, the obtained SPMIA fibers were proved to combine enhanced mechanical properties and unprecedented dyeability. Significantly, the SPMIA fiber with great mechanical property, thermal stability and dyeability shows great potential in easily dyeing high-performance protective fibers.
Homeotropic Alignment and Selective Adsorption of Nanoporous Polymer Film Polymerized from Hydrogen-Bonded Liquid Crystal
Anqi Xiao, Xiaolin Lyu, Hongbing Pan, Zhehao Tang, Wei Zhang, Zhihao Shen, and Xinghe Fan
Accepted Manuscript , doi: 10.1007/s10118-020-2431-9
[Abstract](29) [PDF 1408KB](6)
Nanoporous polymer film with a hexagonal columnar (Colh) structure was fabricated by templated hydrogen-bonding discotic liquid crystals containing methacrylate functional group. The supramolecular hydrogen-bonded complex T3Ph-L is composed of a 1,3,5-tris(1H-benzo[d]imidazol-2-yl)benzene (T3Ph) core molecule as the hydrogen-bonding acceptor and 3,4,5-tris((11-(methacryloyloxy)undecyl)oxy)benzoic acid (L) peripheral molecules as donors. And the Colh structure is always retained after self-assembly, photo-crosslinking, and removal of the template T3Ph. The nanoporous polymer film can retain the Colh phase even under the dry condition, which indicates more possibilities for practical applications. After chemical modification of the inner wall of the nanopores, the nanoporous polymer film with pores of about 1 nm selectively adsorbs ionic dyes, and the adsorption process is spontaneous and exothermic in nature. Homeotropic alignment can be obtained when the blend complex was sandwiched between two modified glasses after annealing by slow cooling, which shows that the nanoporous polymer film has potential in applications such as nanofiltration.
Effects of Branching Strategy on the Gene Transfection of Highly Branched Poly(β-amino ester)s
Yao Wang, Chenfei Wang, Ming Li, Dezhong Zhou, Wei Huang, Wenxin Wang, Deyue Yan
Accepted Manuscript , doi: 10.1007/s10118-020-2393-y
[Abstract](68) [PDF 3350KB](8)
Highly branched poly(β-amino ester)s (HPAEs) have emerged as one type of the most viable non-viral gene delivery vectors, both in vitro and in vivo. However, the effects of different branching strategies on the gene transfection performance have not yet been explored. Here, using triacrylate (B3) and diamine (B4) as the branching monomers, a series of HPAEs were synthesized via the “A2+B3+C2” and “A2+B4+C2” strategies, respectively. Results show that the branching strategy plays a pivotal role in dictating the physiological properties of the HPAE/DNA polyplexes and thus leading to obviously different cell viability and transfection efficiency. Comparatively, HPAEs synthesized via the “A2+B3+C2” branching strategy are more favorable for DNA transfection than that synthesized via the “A2+B4+C2” strategy. This study may provide new insights into the development of HPAEs based non-viral DNA delivery system.
Polymorphic Transition of Pre-oriented Polybutene-1 under Tensile Deformation: In Situ FTIR Study
Zhen Zhang, Xin Chen, Chuang Zhang, Chuntai Liu, Zhen Wang, Yanping Liu
Accepted Manuscript , doi: 10.1007/s10118-020-2409-7
[Abstract](42) [PDF 2018KB](3)
Deformation-induced phase transition of Form II to Form I in polybutene-1 (PB-1) has been investigated by time-resolved Fourier transform infrared (FTIR) spectroscopy over a wide temperature range from 25 to 105 oC. The initial film sample containing orientated lamellae is prepared by pre-stretching of PB-1 melt followed by solidification. This is in order to realize a homogeneity of subsequent deformation at the mesoscale of lamellar stacks by avoiding large-scale spherulites. The deformation induced phase transition is recognized to occur with two stages: first, Form II undergoes the lamellar fragmentation, slipping or local melting after yielding to activate its transition to Form I, which may be realized by releasing the restrictions on chains translational movements in crystalline phase; second, the phase transition proceeds with a continuous dissipation of external work and determines the tensile mechanical response of film. To quantify the relationship between crystalline transition of Form II to Form I and external tensile field, a simple kinetic equation is well established based on FTIR measurement. The equation can describe not only the dependence of crystal transitional degree on applied specific work, but also the retardation effect of elevating temperature on phase transition.
Fabrication of Silver Yolk@Porous Janus Polymer Shell Nanospheres for Synergistic Catalysis
Shaohong Liu, Yanhuan Lin, Wentai Guo, Shimei Li, Weicong Mai, Hui Wang, Ruowen Fu, and Dingcai Wu
Accepted Manuscript , doi: 10.1007/s10118-020-2419-5
[Abstract](25) [PDF 746KB](1)
Yolk-shell nanostructures have recently attracted tremendous research interests in various areas because of their unique structural merits. Currently, there is an urgent need for developing porous shells with multifunctional features to enhance their performance in various applications. Herein, advanced yolk-shell nanospheres have been facilely prepared by encapsulating silver nanoparticles with porous Janus polymer shells that consist of a hypercrosslinked polystyrene (xPS) outer layer and a tethered poly(acrylic acid) (PAA) brush lining. The xPS outer layer possesses well-developed porosity as mass diffusion pathways. More importantly, the tethered PAA brushes with customized carboxyl groups exhibit great affinity toward specific species (e.g., cationic dyes), leading to their enrichment from the bulk solution into the interior cavities. The unusual combination of highly porous outer layers with customizable inbuilt polymer linings in the porous Janus shells makes them great promise for synergistically catalytic degradation of cationic dyes.
Origin of high elastic recovery of hard-elastic polypropylene film at room temperature: The mixed contribution of energy elasticity and entropy elasticity
Jiayi Xie, Ruijie Xu, Caihong Lei
Accepted Manuscript , doi: 10.1007/s10118-020-2432-8
[Abstract](16) [PDF 1984KB](1)
The crystalline and amorphous regions were alternately arranged in the hard elastic polypropylene (PP) films with row-nucleated lamellae. In this work, their structure evolution during stretching and recovery at room temperature was followed and the elastic recovery mechanism was discussed by twice cyclic tensile experiment. During the first stretching to 100%, the lamellae crystals are parallel separated and the intercrystallite crazing is formed at the first yield point. Many nano-cavities within the intercrystallite crazing appear when the strain reaches 20%. The strain-hardening process accompanies with the lamellae long period increasing and the intercrystallite crazing enlargement. After the secondary yield point, the lamellae cluster is further separated and more nano-cavities appear. The first and second recovery process is complete overlap. During recovery, firstly, the energy elasticity provided by nano-cavities surface tension drives the shrinkage of material, and then the entropy elasticity related to amorphous chain relaxation plays a leading role when the strain is smaller than the secondary yield point. The elastic recovery process of hard elastic material is the co-contribution of energy elasticity and entropy elasticity. This work gives a clearer recognition about the source of hard elastic property and the role of amorphous region in material’s deformation.
A Self-assembled Nanoparticle Platform Based on Amphiphilic Oleanolic Acid Polyprodrug for Cancer Therapy
Ying-Sa Wang, Gui-Liang Li, Shang-Bin Zhu, Fan-Chen Jing, Run-Dong Liu, Sai-Sai Li, Jing He, Jian-Du Lei
Accepted Manuscript , doi: 10.1007/s10118-020-2401-2
[Abstract](54) [PDF 2435KB](6)
Oleanolic acid (OA) is a pentacyclic triterpenoid compound with extensive biological effects, such as anti-inflammatory and anticancer activities. However the application of OA in chemotherapy is hampered by its poor solubility and severe adverse effects. To solve the problems, we developed a self-assembled nanoparticle platform based on amphiphilic oleanolic acid polyprodrug, poly[oligo(ethylene glycol) methyl ether methacrylate]-b-poly[oleanolic acid methacrylate] (POEGMA-b-POAMA), encapsulating 10-hydroxycamptothecin (HCPT) to achieve efficient cancer therapy. The polyprodrug was prepared via reversible addition-fragmentation chain transfer polymerization (RAFT), and could self-assemble to prepare POEGMA-b-POAMA/HCPT nanoparticles (NPs). The obtained nanoparticles exhibited appropriate particle size, excellent drug stability, good drug loading capacity and high drug loading efficiency. In vitro drug release indicated that the drug release was prolonged to 132 h. The POEGMA-b-POAMA/HCPT NPs enhanced cell cytotoxicity in 4T1 cells and MCF-7 cells and could be efficiently uptaken by 4T1 cells. Furthermore, in vivo antitumor efficiency showed that the POEGMA-b-POAMA/HCPT NPs had great antitumor efficiency with considerably low adverse effects in the treatment of the 4T1 mouse breast tumor xenograft tumor. Therefore, POEGMA-b-POAMA/HCPT NPs provide great potential as a platform for drug delivery applications.
Xinran Liu, Yu Wang, Liyuan Liu, Xia Dong, and Dujin Wang
Accepted Manuscript , doi: 10.1007/s10118-020-2434-6
[Abstract](19) [PDF 977KB](0)
The rheological property evolution of polyamide 1012 (PA1012) during the isothermal process in molten state has been investigated. The results show that the viscosity increases and crosslinking reaction occurs simultaneously together with the increase of temperature, thus causing the variation of elastic modulus (G’) and loss modulus (G”) in the repeated frequency sweeps with residual time. This research has pointed out that the superposition is valid for monitoring the complex behavior composed of the viscosity increasing and crosslink occurring process by tracing the variation behavior of the crossover points of G’ and G” with time, revealing the same time-temperature dependence of the two reactions during the isothermal process. A normalized master curve has been proposed to describe the melt behavior at a given temperature.
Construction of Ionic Porous Organic Polymers (iPOPs) via Pyrylium Mediated Transformation
Shi-Yue Zhang, Wei-Tao Gong, Wei-Dong Qu, Xiao-Rong Deng, Kai-Xun Dong, Shu-Guang Zhang, and Gui-Ling Ning
Accepted Manuscript , doi: 10.1007/s10118-020-2436-4
[Abstract](12) [PDF 753KB](0)
Two new ionic porous organic polymers (iPOPs) with different counter anions were successfully fabricated via well-known pyrylium mediated transformation into pyridinium. 13C solid-state NMR, XPS, and FTIR were analyzed and confirmed the formation of pyridinium in the network. Containing charged and aromatic networks, both iPOPs exhibit a high affinity towards toxic hexavalent chromium Cr(VI) ions. What’s more, it has been demonstrated that both CO2 adsorption and Cr(VI) removal properties can be tuned by simply varying counter anions.
Synthesis and Properties Investigation of Thiophene-aromatic Polyesters: Potential Alternatives for the 2,5-Furandicarboxylic acid-based Ones
Jinggang Wang, Xiaoqin Zhang, Ang Shen, Jin Zhu, Pingan Song, Hao Wang and Xiaoqing Liu
Accepted Manuscript , doi: 10.1007/s10118-020-2438-2
[Abstract](8) [PDF 1571KB](0)
In order to explore new substitutes for 2,5-furandicarboxylic acid (FDCA) or poly(ethylene 2, 5-furandicarboxylate) (PEF), and try to develop more ideal bio-based polyesters, several thiophene-aromatic polyesters (PETH, PPTH, PBTH and PHTH) were synthesized from dimethyl thiophene-2,5-dicarboxylate (DMTD) and different diols, including ethylene glycol, 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol. The chemical structures of obtained polyesters were confirmed by nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR). Determined by GPC measurement, their average molecular weight (Mw) varied from 52200 to 79400 g/mol with the molar-mass dispersity of 1.50-2.00. Based on the DSC and TGA results, the synthesized polyesters PETH, PPTH and PBTH displayed comparable or even better thermal properties when compared with their FDCA-based analogues. From PETH to PHTH, their Tg was varied from 64.6 to -1 oC, as well as the T5% ranged from 409 to 380 oC in nitrogen atmosphere. PETH showed elongation at break as high as 378%, tensile strength of 67 MPa and tensile modulus of 1800 MPa. Meanwhile, both the CO2 and O2 barrier of PETH were respectively 12.0 and 6.6 fold higher than PET, similar to those of PEF. Considering the overall properties, the synthesized thiophene-aromatic polyesters, especially PETH, showed great potential to be used as an excellent bio-based packaging material in the future.

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2020, 38(4) .  
[Abstract](458) [PDF 45504KB](1)
Melt Crystallization of Poly(butylene 2,6-naphthalate)
Qian Ding, Michelina Soccio, Nadia Lotti, Dario Cavallo, René Androsch
2020, 38(4): 311 -322.   doi: 10.1007/s10118-020-2354-5
[Abstract](334) [FullText HTML](120) [PDF 1495KB](22)
Poly(butylene 2,6-naphthalate) (PBN) is a crystallizable linear polyester containing a rigid naphthalene unit and flexible methylene spacer in the chemical repeat unit. Polymeric materials made of PBN exhibit excellent anti-abrasion and low friction properties, superior chemical resistance, and outstanding gas barrier characteristics. Many of the properties rely on the presence of crystals and the formation of a semicrystalline morphology. To develop specific crystal structures and morphologies during cooling the melt, precise information about the melt-crystallization process is required. This review article summarizes the current knowledge about the temperature-controlled crystal polymorphism of PBN. At rather low supercooling of the melt, with decreasing crystallization temperature, β′- and α-crystals grow directly from the melt and organize in largely different spherulitic superstructures. Formation of α-crystals at high supercooling may also proceed via intermediate formation of a transient monotropic liquid crystalline structure, then yielding a non-spherulitic semicrystalline morphology. Crystallization of PBN is rather fast since its suppression requires cooling the melt at a rate higher than 6000 K·s−1. For this reason, investigation of the two-step crystallization process at low temperatures requires application of sophisticated experimental tools. These include temperature-resolved X-ray scattering techniques using fast detectors and synchrotron-based X-rays and fast scanning chip calorimetry. Fast scanning chip calorimetry allows freezing the transient liquid-crystalline structure before its conversion into α-crystals, by fast cooling to below its glass transition temperature. Subsequent analysis using polarized-light optical microscopy reveals its texture and X-ray scattering confirms the smectic arrangement of the mesogens. The combination of a large variety of experimental techniques allows obtaining a complete picture about crystallization of PBN in the entire range of melt-supercoolings down to the glass transition, including quantitative data about the crystallization kinetics, semicrystalline morphologies at the micrometer length scale, as well as nanoscale X-ray structure information.
Achieving Efficient Thick Film All-polymer Solar Cells Using a Green Solvent Additive
Zhen-Ye Li, Wen-Kai Zhong, Lei Ying, Ning Li, Feng Liu, Fei Huang, Yong Cao
2020, 38(4): 323 -331.   doi: 10.1007/s10118-020-2356-3
[Abstract](347) [FullText HTML](89) [PDF 440KB](34)
Advances in organic photovoltaic technologies have been geared toward industrial high-throughput printing manufacturing, which requires insensitivity of photovoltaic performance regarding to the light-harvesting layer thickness. However, the thickness of light-harvesting layer for all polymer solar cells (all-PSCs) is often limited to about 100 nm due to the dramatically decreased fill factor upon increasing film thickness, which hampers the light harvesting capability to increase the power conversion efficiency, and is unfavorable for fabricating large-area devices. Here we demonstrate that by tuning the bulk heterojunction morphology using a non-halogenated solvent, cyclopentyl methyl ether, in the presence of a green solvent additive of dibenzyl ether, the power conversion efficiency of all-PSCs with photoactive layer thicknesses of over 500 nm reached an impressively high value of 9%. The generic applicability of this green solvent additive to boost the power conversion efficiency of thick-film devices is also validated in various bulk heterojunction active layer systems, thus representing a promising approach for the fabrication of all-PSCs toward industrial production, as well as further commercialization.
Hierarchically Crosslinked Gels Containing Hydrophobic Ionic Liquids towards Reliable Sensing Applications
Xia-Chao Chen, Pei-Ru Sun, Hong-Liang Liu
2020, 38(4): 332 -341.   doi: 10.1007/s10118-020-2357-2
[Abstract](330) [FullText HTML](108) [PDF 760KB](25)
Human skin can function steadily regardless of surrounding circumstances (dry or wet), while it is still a challenge for artificial ionic skins, which tend to release solvents in dry air and leach electrolytes in wetted state. Herein, a series of hierarchically crosslinked ionogels containing hydrophobic ionic liquids (ILs) is fabricated by combining a crystalline fluorinated copolymer with hydrophobic ILs. With a reasonable combination of nonvolatility, transparency, stretchablility, and sensitivity, such ionogels can work as reliable sensors for real-time monitoring human motions and operate steadily in complex environments as human skin does, which can contribute to the development of durable sensing devices with a simple design.
Unsymmetric Side Chains of Indacenodithiophene Copolymers Lead to Improved Packing and Device Performance
Ying Yang, Tong Shan, Jian Cao, Hua-Chun Wang, Ji-Kang Wang, Hong-Liang Zhong, Yun-Xiang Xu
2020, 38(4): 342 -348.   doi: 10.1007/s10118-020-2342-9
[Abstract](374) [FullText HTML](138) [PDF 446KB](25)
Two conjugated polymers (PuIDTBD and PuIDTQ) with unsymmetric side chains have been prepared for polymer solar cells using two other polymers (PIDTBD and PIDTQ) with symmetric side chains as control compounds. The combination of methyl and 4-hexylphenyl side chains on the same bridged carbon can ensure good solubility, decrease π-π stacking distances, and bring proper miscibility with PC71BM simultaneously. Therefore, the corresponding polymer solar cells (PSCs) based on donor polymers with unsymmetric side chains exhibited enhanced short-circuit current density (JSC) and power conversion efficiency (PCE) compared with those of control polymers. The PIDTBD and PIDTQ based devices possessed low PCE of 2.13% and 1.48%, while PCEs of devices based on PuIDTBD and PuIDTQ were improved to 3.93% and 4.12%, respectively. The results demonstrate that unsymmetric side chain engineering of conjugated polymers is an effective approach to achieve high performance PSCs.
Ultrasound-responsive Homopolymer Nanoparticles
Bo Yang, Jian-Zhong Du
2020, 38(4): 349 -356.   doi: 10.1007/s10118-020-2345-6
[Abstract](557) [FullText HTML](113) [PDF 890KB](31)
Noninvasive ultrasound is a more effective strategy for on-demand drug delivery of polymeric nanoparticles than many other stimuli. However, the preparation of ultrasound-responsive homopolymer nanoparticles is still very challenging. In this study, we disclose the regulating factors of ultrasound responsiveness of homopolymer nanoparticles and the disaggregation behavior of homopolymer nanoparticle aggregates. Homopolymer nanoparticles such as vesicles and large compound micelles (LCMs) are self-assembled from poly(methoxyethyl methacrylate) (PMEMA) and poly(amic acid) (PAA), respectively. The ultrasound responsiveness of PAA vesicles at metastable state could be regulated by tuning the self-assembly temperature (Ts), and was optimized when Ts is around the glass transition temperature (Tg) of PAA. However, the PMEMA LCMs did not respond to ultrasound as they are at stable state. On the other hand, poly(2-(2-ethoxyethoxy)ethyl acrylate) (PEEA) could self-assemble into vesicle aggregates or complex micelle aggregates, which were dissociated upon sonication. Overall, the above findings provide us with a fresh insight for designing ultrasound-responsive polymeric nanoparticles.
Anionic Polymerization of Butadiene Using Lithium/Potassium Multi-metallic Systems: Influence on Polymerization Control and Polybutadiene Microstructure
Antoine Forens, Kevin Roos, Charlotte Dire, Benoit Gadenne, Stéphane Carlotti
2020, 38(4): 357 -362.   doi: 10.1007/s10118-020-2355-4
[Abstract](294) [FullText HTML](105) [PDF 240KB](15)
Thermal, mechanical, and viscoelastic properties of polybutadiene-based rubber materials are highly dependent on polybutadiene microstructure. The use of polar modifier in association with alkyllithium is a well-known method to obtain polybutadiene with a high vinyl content. Another approach is to use bimetallic initiating species such as alkyllithium combined to heavier alkali metal alkoxide (RONa, ROK…). The polymerization control is nevertheless not achieved and several parameters were found to influence it. Using bimetallic initiating systems based on alkyllithium and a potassium alkoxide, alkyllithium structure, initiator preformation time, and initiator composition were identified as parameters influencing the anionic polymerization process of butadiene and/or polybutadiene microstructure. In addition, the use of trimetallic systems based on alkyllithium, potassium alkoxide, and alkylaluminum was investigated in order to prevent side reactions regardless of the [K]/[Li] ratio and of the initiator preformation time.
Role of Hydrodynamic Interactions in the Deformation of Star Polymers in Poiseuille Flow
Zhen-Yue Yang, Xiao-Fei Tian, Li-Jun Liu, Ji-Zhong Chen
2020, 38(4): 363 -370.   doi: 10.1007/s10118-020-2346-5
[Abstract](408) [FullText HTML](149) [PDF 1661KB](28)
Stretching polymer in fluid flow is a vital process for studying and utilizing the physical properties of these molecules, such as DNA linearization in nanofluidic channels. We studied the role of hydrodynamic interactions (HIs) in stretching a free star polymer in Poiseuille flow through a tube using mesoscale hydrodynamic simulations. As increasing the flow strength, star polymers migrate toward the centerline of tube due to HIs, whereas toward the tube wall in the absence of HIs. By analyzing the end monomer distribution and the perturbed flow around the star polymer, we found that the polymer acts like a shield against the flow, leading to additional hydrodynamic drag forces that compress the arm chains in the front of the star center toward the tube axis and lift the arm chains at the back toward the tube wall. The balanced hydrodynamic forces freeze the polymer into a trumpet structure, where the arm chains maintain a steady strongly stretched state at high flow strength. In contrast, the polymer displays remarkably large conformational change when switching off HIs. Our simulation results explained the coupling between HIs and the structure of star polymers in Poiseuille flow.
Conformational Properties of Comb-shaped Polyelectrolytes with Negatively Charged Backbone and Neutral Side Chains Studied by a Generic Coarse-grained Bead-and-Spring Model
Jian-Hua Chen, Li-Qun Lu, Hong-Xia Zhao, Yong Yang, Xin Shu, Qian-Ping Ran
2020, 38(4): 371 -381.   doi: 10.1007/s10118-020-2350-9
[Abstract](349) [FullText HTML](102) [PDF 368KB](13)
A generic coarse-grained bead-and-spring model, mapped onto comb-shaped polycarboxylate-based (PCE) superplasticizers, is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions. The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution. The effects of ionic strength, side-chain number, and side-chain length on the conformational behavior of PCEs in solution are explored. Single-chain equilibrium properties, including the radius of gyration, end-to-end distance and persistence length of the polymer backbone, shape-asphericity parameter, and the mean span dimension, are determined. It is found that with the increase of ionic strength, the equilibrium sizes of the polymers decrease only slightly, and a linear dependence of the persistence length of backbone on the Debye screening length is found, in good agreement with the theory developed by Dobrynin. Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes (radius of gyration and mean span) of the polymer as a whole, but also the persistence length of the backbone due to excluded volume interactions.
General Model of Temperature-dependent Modulus and Yield Strength of Thermoplastic Polymers
Ping-Yuan Huang, Zhan-Sheng Guo, Jie-Min Feng
2020, 38(4): 382 -393.   doi: 10.1007/s10118-020-2360-7
[Abstract](328) [FullText HTML](115) [PDF 834KB](19)
A general model was developed to predict the temperature-dependent modulus and yield strength of different thermoplastic polymers. This model, which depends on only two parameters with clear and specific physical meanings, can describe the temperature-dependent modulus and yield strength of thermoplastic polymers over the full glass transition region. The temperature-dependent modulus and yield strength of three thermoplastic polymers were measured by uniaxial tension tests over a temperature range of 243−383 K. The predictions showed excellent agreement with the experimental data. Sensitivity analysis of model input parameters showed negligible effect on the present general model. The universality of the present general model was further validated, showing excellent agreement with published experimental data on other thermoplastic polymers and their composites.
Surface Patterns of a Tetrahedral Polyelectrolyte Brush Induced by Grafting Density and Charge Fraction
Hong-Ge Tan, Gang Xia, Li-Xiang Liu, Xiao-Hui Niu, Qing-Hai Hao
2020, 38(4): 394 -402.   doi: 10.1007/s10118-020-2351-8
[Abstract](314) [FullText HTML](125) [PDF 1076KB](7)
A tetrahedral polyelectrolyte brush in the presence of trivalent counterions is researched under the condition of good solution by means of molecular dynamics simulations. Grafting density and charge fraction are varied to generate a series of surface patterns. Lateral microphase separation happens and various interesting pinned patches appear at appropriate charge fraction and grafting density. Through a careful analysis on the brush thickness, the pair correlation functions, the distributions of net charge, and the four states of trivalent counterions in the brush, we find that the ordered surface patterns and special properties are induced by the pure electrostatic correlation effect of trivalent ions even in the good solvent. Furthermore, the dependences of electrostatic correlation on the charge fraction of tethered chains are evaluated for fixed grafting density. Also, our results can serve as a guide for precise control over the stimuli-responsive materials rational and self-assembly of nanoparticles.