最新刊期
卷 36 ， 期 4 ， 2023
- 摘要：Silk fibroin has good biocompatibility, biodegradability and low inflammatory response in vivo, and has broad application prospects in the field of biomedicine. However, the mechanical properties and biological activities of regenerated silk fibroin materials need to be further improved to meet the needs of different tissue engineering. Cellulose possesses a wide range of sources, low cost, and good mechanical properties. The reinforced composite materials prepared from cellulose and its derivatives have attracted widespread attention. Using cellulose and silk fibroin as raw materials to prepare high-performance composites with different solvent systems has become an interesting work in the field of natural polymers in recent years. In this paper, the structure, properties and related applications of silk fibroin and cellulose are introduced. The solvent systems of cellulose and silk fibroin are classified. Recent progress of various cellulose/silk fibroin composite forms (films, gels, fibers, etc.) are reviewed.关键词：Cellulose;Silk fibroin;Composite material;Biomedical
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发布时间：2023-02-18 - 摘要：With the advent of wearable electronics and smart textiles, the strong need for energy saving and efficient personal thermoregulation has attracted widespread attention from researchers. To achieve human thermal comfort, personal thermal management has become an important strategy to regulate and balance the heat exchange between the human body and the surrounding environment. As the interface for material and energy exchange between the human body and the environment, fabrics play an indispensable and important role in controlling the microclimate around the human skin. Smart fibers and textiles with light weight, good mechanical flexibility, multi-responsiveness, and excellent temperature regulation are urgently needed in personal thermal management applications. This article describes emerging materials and strategies for personal thermal management and categorizes them according to their thermal functions, including personal cooling, heating, and thermos-stating according to specific application areas and individual needs. Finally, critical thinking is also given on the opportunities and challenges of smart fibers and textiles for personal thermal management applications.关键词：Smart fibers and textiles;Personal thermal management;Cooling/heating;Thermal radiation;Selfthermoregulation
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发布时间：2023-02-18 - 摘要：High temperature proton exchange membrane fuel cells (HT-PEMFCs), can be directly fed with reformed gas therefore simplify the hydro-thermal management, due to their strong CO resistance, which can effectively solve the problem of hydrogen source and help achieve the carbon peaking and carbon neutrality goals. As the core component of HT-PEMFCs, high temperature proton exchange membrane (HT-PEM) has attracted much attention in recent years, especially for the most promising phosphoric acid-doped polybenzimidazole (PAPBI) electrolyte membrane. PA-PBI has many advantages, such as high mechannical/thermal/chemical stability and anhydrous proton conductivity. However, these advantages are not outstanding enough and there are still many shortcomings of traditional PA-PBI: In terms of membrane performance and operating life time, the contradiction between high proton conductivity and high mechanical properties, easily damaged by thermal stress during operating and excessive phosphoric acid loss of PA-PBI, etc. restrict the the full-scale application of traditional PA-PBI in HT-PEMFCs. Other defects like poor film-forming properties would influence the fabrication of PA-PBI membrane. This review article is aimed to summarize some research progresses on PA-PBI, including the synthesis of PBI molecular, preparation process of PA-PBI membrane, proton transport mechanism and the the methods for improving the performance and operating life time of PA-PBI membranes such as molecular structure modification, grafting, cross-linking, and organic-inorganic composite doping are mainly discussed and prospect the future development of PA-PBI electrolyte membrane. Although the commercial application of PAPBI in HT-PEMFCs is still a long way off, scientists are gradually narrowing this distance, especially in terms of balancing proton conductivity, mechanical properties and operating lifetime of PA-PBI for the best application point. At the same time, the research on how to increase the operating temperature of PA-PBI to further enhance the performance of HT-PEMFCs has gradually attracted attention. It is believed that the full-scale application of PA-PBI in HT-PEMFCs will become a reality in the near future.关键词：Polybenzimidazole;High temperature proton exchange membrane fuel cell;High temperature proton exchange membrane polymer;Molecular modification
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发布时间：2023-02-18 - 摘要：Polymer hydrogel is a kind of polymer material which has wide application prospect in medicine, pharmacy, cartilage tissue engineering, artificial muscle, bionic brake and adsorbent. However, its applications are limited largely because of its low mechanical strength. In recent years, polymer reinforced hydrogels have attracted extensive attention from many scientists at home and abroad. It has been proven that the reinforced polymer hydrogels have the characteristics of anti-swelling, strong toughness and ultra-high mechanical strength, which possess significant application value. This paper introduces the concept of polymer hydrogel and its reinforcing mechanisms. And the strategies of preparation of polymer reinforced hydrogels are summarized in detail, including the preparation of hydrogels by immersion in electrolyte solutions, nanocomposites hydrogels and multinetwork hydrogels. Finally, based on some problems existing in current polymer hydrogel (such as some hydrogels have poor biocompatibility, cannot be degraded in human body and poor conductivity), the future development of polymer reinforced hydrogels and their application in natural materials, biology and environmental remediation are prospected.关键词：Polymer hydrogels;Reinforcement;Preparation strategies;Mechanisms
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发布时间：2023-02-18 - 摘要：Glycolide is used to synthesize polyglycolic acid, which is highly demanded due to the promising mechanical property, biocompatibility and especially biodegradability for sustainable developement. The synthesis of polyglycolic acid is therefore significantly affected by the glycolide. Glycolide is generally prepared from glycolic acid (ester). However, the polycondensation of glycolic acid (ester) requires high energy consumption including vacuum and high temperature. Herein, we report a azeotropic polycondensationdepolymerization method for the synthesis of glycolide, enabling the polycondensation of glycolic acid into polyglycolic acid oligomers under mild conditions with recoverable solvent and no catalyst, which are subsequently depolymerized into glycolide finally. Polyglycolic acid oligomers was comprehensively characterized as a kind of semi-crystalline polymers with the number average molecular weight of 1900 g/mol and the crystallinity of 33.1% by X-ray powder diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and other methods. The glycolide product is obtained from the depolymerization polyglycolic acid oligomers with a yield of 81.26% and a purity of 89.29%. Furthermore, the depolymerization reaction residues of polyglycolide acid oligomers can be reused to produce more glycolide. Our method provides a green way for the production of glycolide and polyglycolic acid oligomers, and should contribute to the sustainable development and energy-saving of polyglycolic acid in the areas of material, industry and environment关键词：Glycolic acid;Polyglycolic acid oligomers;Glycolide;Polycondensation;Depolymerization
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发布时间：2023-02-18 - 摘要：A composite with resistance-strain response characteristics was obtained by blending multi-walled carbon nanotube (MWCNT) to modify chloroprene rubber (CR). With the increase of carbon nanotube content, the strength and stiffness of the material increased significantly. The conductive percolation threshold of MWCNT content is 4.75 wt%, and if the content exceeds this value, the MWCNT form a tunneling conductive network inside the rubber matrix, and thus the material has conductive ability. The resistance-strain response test analysis of the material under static and cyclic loading shows that when the content of MWCNT is 8 wt%, the resistance-strain response gauge factor GF>418, showing good strain sensing characteristics. With the increase of MWCNT content, GF value decreases gradually, and the stability of resistance-strain response decreases, and shoulder peak effect appears, which proves that excessive carbon nanotube content has an adverse effect on the damage and reconstruction of conductive network with deformation. Finally, the mechanism of above resistancestrain response was analyzed by digital image correlation (DIC) method and the theoretical model of electron tunneling effect.关键词：Multi-walled carbon nanotube;Chloroprene rubber;Resistance-strain response;Large strain monitoring;Tunneling effect
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发布时间：2023-02-18 - 摘要：In this work, the hydroxyl-terminated polybutadiene acrylonitrile liquid rubber (HTBN) was modified and blocked different photoactive end functional groups to prepare photoreactive telechelic polybutadiene acrylonitrile oligomers. After compounding with active small molecule and photoinitiator, as well as UV-light curing, polybutadiene acrylonitrile-based polyurethane (BNPU) dielectric elastomers with different molecular chain structures were fabricated. The results showed that with the increase of the molecular chain length in the HTBN precursor, the entanglement network density of the cured BNPU elastomers increased, further to provide a high Young’s modulus (Y) of utmost 1.89 MPa and a large elongation at break (EB) of 112.26% to the elastomer, respectively. The long molecular chain between crosslinking points can also reduce the glass transition temperature (Tg) of the elastomers. The BNPU elastomer which was cured from HTBN oligomer with pentaerythritol triacrylate (PETA) end-blocked can form partial cross-linking domains with large volume steric hindrance, endowing the BNPU elastomers with increased Tg, decreased thermal decomposition velocity and enhanced inter facial polarization between separated microphase. As a result, the dielectric properties of the BNPU elastomers with partial cross-linking regions were improved. For instance, the dielectric constant (ε') of BNPU elastomer sample reached a maximum value of 807 under 103 Hz, and its dielectric loss (tanδ) can be maintained below 1. One can make a conclusion that the synergistic effect between partial cross-linking domains with large volume hindrance and cyan side groups can guarantee the BNPU elastomer an excellent comprehensive electromechanical property, proposing a solution to the issues of high modulus and low breakdown strength for pure polyurethane and highly cross-linked nitrile rubber.关键词：Hydroxyl terminated butyl nitrile (HTBN);Polyurethane (PU) elastomer;Molecular structure;Partial crosslinking;Dielectric properties
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发布时间：2023-02-18 - 摘要：The microstructure of polydienes directly affects the elasticity, crystallinity, heat resistance, hydrogenation, damping and other properties of the product. In order to explore the influence of tetrahydrofuranyl [N,O]-chelated polar-additives (PA) on microstructure of anionic polymerization of conjugated dienes, four high-efficient PAs including N, N-dimethyl-tetrahydrofurfuralamide (DMTHFA), N-tetrahydrofuromorpholine (THFM), N-tetrahydrofuropipine (THFHP) and N-tetrahy- drofurfuryl pyrrole (THFP) were selected to coinitiate butadiene (BD), isoprene (IP) and 1,3-pentadiene (PD) polymerization with n-BuLi. It is also compared with tetrahydrofuran (THF) commonly used in industry. The results based on 1H-NMR data showed that: (1) all PAs had highly efficient regulation (molar ratio, PA/Li≤4.0), which can be used for the production of medium and high branched polybutadiene and polyisoprene rubber. However, the 1,2-polypentadiene can only be regulated in the range of 20%~38% due to its special molecular conformation; (2) under the effect of DMTHFA and THFM, the branched structure of polybutadiene and polyisoprene decreased with increasing temperature, but the 1,2-polypentadiene increased slightly. Interestingly, the DMTHFA is not sensitive to temperature; (3) the amplification experiment showed that PA can significantly increase the polymerization rate and the regulation ability is better than that of the ether regulator used in industry equipment. Moreover, the PA had positive effect on the hydrogenation degree of the SBS, which has the prospect of industrialization.关键词：[N,O]-chelated polar-additives;Conjugated diene;Anionic polymerization;Microstructure;Branch structure
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发布时间：2023-02-18 - 摘要：The models of diglycidyl ether of bisphenol A (DGEBA) epoxy with diethanolamine (DEA) and thermo-oxidative aging DEA/DGEBA were built via the combined method of molecular dynamic methods and perl script. The effect of oxidation degree and crosslinking degree on glass transition temperature (Tg) and modulus of epoxy resins were studied by orthogonal experiment and range analysis. The simulation results show that under the condition of a higher degree of crosslinking, the degree of oxidation has a stronger effect on the mechanical properties of DEA/DGEBA system than the degree of crosslinking, while the effect on the glass transition temperature is opposite. The results are consistent with the curing experiments. These results could be used to understand the usual modulus curve that first increased and then decreased found on thermo-oxidative aging experiment for DEA/DGEBA.关键词：Epoxy resin;Thermo-oxidative degradation;Molecular dynamics simulation;Crosslink
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发布时间：2023-02-18 - 摘要：Coagulation is a commonly physiological and pathological phenomenon. The occurrence of coagulation is a cascade of chemical reactions. Firstly, the coagulation factors generate the activator of prothrombin under the trigger of internal or external stimuli, so that the prothrombin is converted into thrombin. Secondly, the polypeptide chain is removed from fibrinogen with the activation of thrombin and fibrinogen is converted into the monomers of fibrin, which are polymerized to form the polymer of fibrin. Thirdly, fibrin combines with platelets, red blood cells, and endothelial cells in the blood and finally they form a network of blood clot. In this study, the molecular reactions and the structural changes of thrombin and fibrin in the coagulation have been analyzed from the perspective of macromolecular chemistry and physics.关键词：Coagulation;Biomacromolecules;Thrombin;Fibrin;Polymer chemistry
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发布时间：2023-02-18 - 摘要：The design and development of self-healing and reusable thermosetting materials became one of the hot topics in polymer materials study in recent years. In this paper, terephthalaldehyde, dipolyetheramine and ternary polyetheramine were employed as the raw materials to prepare such kind of thermosetting materials with Schiff base-type cross-linked network structure. The materials showed great self-healing and remodeling behavior due to the rapid and reversible imine network rearrangement reaction occurs at the temperature of 80~100 ℃ among the large amount of imine bonds (—C=N—). Owing to the advantages of mild reaction conditions and convenient operations, the procedure is suitable to be promoted as a teaching experiment for material majors and a popular science experiment for high school students.关键词：Dynamic covalent bonds;Schiff base;cross-link;Self-healing;Remold;Undergraduate experiment teaching
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发布时间：2023-02-18 - 摘要：Based on the development of engineering education accreditation, cultivating students’ ability to solve complex engineering issues through professional courses has become the key to implementing the graduation requirements, but how to extract complex engineering problems related to majors and integrate the teaching process has become a common problem in the teaching of current professional courses. "Polymer Physics" is one of the core basic courses of polymer materials and engineering, this work takes "Polymer Physics" as an example, sets the output-oriented course objectives around the graduation requirements, and forms a complex engineering issue case library by refining and simulating the real scenes of complex engineering activities, and establishes a case-based classroom teaching mode of complex polymer physics and engineering. The practice of teaching reform shows that case-based classroom teaching has achieved good results in cultivating students’ ability to solve engineering practice problems.关键词：Polymer physics;Engineering education accreditation;Case-based teaching;Complex engineering issues
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发布时间：2023-02-18 - 摘要：During the construction of new engineering courses, some core engineering courses face several typical problems. For one example, students are not interested in these courses, because they think that they are not going to find a "low-level" job in factories producing polymers. For another example, the course content is abstract, and the knowledge is spread, out-of-date or even boring. In this paper, taking "Principles and Technologies of Polymer Synthesis" as a representative course, we analyzed the "pain points" of the course, and developed effective strategies to solve these for "pain points" . These strategies evidently improved the teaching outcoming, and students’ engineering consciousness and ability to solve complex engineering problem. Therefore, this study will provide some guidelines for cultivating talented engineers who not only master technologies of polymerization, but also know how to organize and manage a polymerization factory.关键词：New engineering talents;Polymerization technologies;Process simulation;Teaching innovation
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发布时间：2023-02-18
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