最新刊期
卷 33 ， 期 3 ， 2020
- 摘要：The application of functional fillers into silicone rubber and its composite materials to obtain specific functions of silicone rubber composite materials has become a research hotspot in recent years. At present, there are many kinds of flame retardants, but the performance is relatively simple, which can not meet the needs of people. While the flame retardant properties of silicone rubber composites have attracted attention, other issues such as performance and cost have also been considered. Therefore, the flame retardant research status of silicone rubber composites mixed with flame retardants such as platinum compounds, phosphorus flame retardants, flame retardant coatings, flame retardant fillers and microencapsulated flame retardants are discussed. The flame retardant mechanisms of different flame retardants are summarized, then its future improvement methods are pointed out. At last, the development of flame retardant research on silicone rubber composites is prospected.关键词：Silicone rubber composites;Flame retardancy;Flame retardant mechanism;Research progress
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发布时间：2022-08-31 - 摘要：Reversible addition-fragmentation chain transfer polymerization (RAFT) is an effective controlled/living free radical polymerization method. It is widely used in the preparation of functional polymers. The key to RAFT polymerization is to select the appropriate RAFT agent. The preparation of water-soluble RAFT agents is critical based on environmentally sound and non-hazardous requirements. The paper introduces the mechanism of RAFT polymerization and summarizes the preparation and application of water-soluble RAFT agents. The mechanism of water solubility of RAFT chain transfer agent was discussed. On the one hand, the role of polar group, on the other hand, the role of ionic bond hydrogen bond etc. that has certain enlightenment for the preparation of water-soluble RAFT agent. The macro-RAFT agent often contains hydrophilic groups and hydrophobic groups with dispersion effect. Under the aqueous phase condition, not only a narrow molecular weight distribution block copolymer can be prepared by chain extension reaction, but also micro/nano-gel can be prepared.关键词：Reversible addition-fragmentation chain transfer polymerization;RAFT agent;Water solubility;Progress
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发布时间：2022-08-31 - 摘要：This paper mainly concentrates on the synthesis of PANI by using several different natural biomolecules such as proteins (including the enzymes and amino acids), sugars, nucleic acids, dopamine and lemon juice. Firstly, we introduced the effects of natural biomolecules on the chirality, electrical conductivity and morphology of conducting polyaniline and the research progress on the synthesis of conducting polyaniline by using natural biomolecules are summarized. Then, the problem existed in the synthesis of PANI is analyzed and the future prospects in this field are discussed, which can provide useful references to the preparation of environment friendly conducting PANI with excellent properties.关键词：Polyaniline;Natural biomolecule;Electrical conductivity;Research progress
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发布时间：2022-08-31 - 摘要：In this study, high specific surface area and stable skeleton, functional hybrid mesoporous MCM-41-PAA was prepared using diatomite as a silicon source, CTAB as a template, and polyacrylic acid as a dopant based on mesoporous materials with a uniform adjustable pore size structure. The composition, structure and morphology of MCM- 41-PAA were characterized by FT-IR, XRD, SEM and nitrogen adsorption and desorption. MCM-41-PAA, as an adsorbent, was used to adsorb mercury ions, and the factors such as the dosage of the adsorbent, the initial Hg(II) ions concentration, the pH value of solution and the adsorption time were explored. The results showed that the adsorption capacity could reach 132mg/g when the dosage of adsorbent, the concentration of Hg(II) ions, the pH and the adsorption time were 0.2g, 300mg/L, 4 and 180min, respectively.关键词：Diatomite;Polyacrylic acid;Mesoporous materials;Absorption;Hg(II) ions
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发布时间：2022-08-31 - 摘要：Poly(lactic acid)(PLA)/chitosan(CS) composite nanofibrous scaffolds were fabricated from a quaternary PLA/CS/dioxane/glacial acetic acid system by phase separation method. The effects of gelation temperature, CS content and the molecular weight of PLA on the morphology of composite scaffolds were investigated. The results revealed that gelation temperature and the molecular weight of PLA significantly influenced the formation of nanofibrous structure, but the CS content had very litter effect on the nanofibrous structure. The microstructure of the PLA/CS composite scaffolds changed greatly with the reduction of gelation temperature, from nano-structure to micro-structure. Besides, high molecular weight of PLA make for nanofibrous structure easier than the low molecular weight of PLA in this work. The mineralization results showed that PLA/CS composite nanofibrous scaffolds could induce hydroxyapatite formation faster than pure PLA nanofibrous scaffolds.关键词：Poly(lactic acid);Chitosan;Nanofibrous;Bioactivity
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发布时间：2022-08-31 - 摘要：Based on the host-guest interaction, HPEI-CDs/Azo-PEG/DNA polyplexes was prepared by β-cyclodextrin modified with polyethyleneimine (HPEI-CDs) and azobenzene-conjugated with polyethylene glycol (Azo-PEG). The stability of its physiological salt condition, size, morphology and photo response were studied. The results showed that compared with HPEI-CDs/DNA polyplexes, the introduction of PEG significantly improved the stability under physiological salt condition. With the synergistic effect of PEG shell charge screening and CD hydrogen bonding, the surface potential of polyplexes was only +3mV, uniform and spherical microparticles were achieved. The surface potential of HPEI-CDs/Azo-PEG/DNA increased rapidly under 365nm wavelength illumination. With the extension of illumination time, ζ potential eventually increased to a level close to that of HPEI-CDs/DNA, it indicated that azobenzene (Azo) was transformed from trans to cis-structure, light irradiation made Azo-CD inclusion complexes disassemble and lead to PEG shell detachment.关键词：Photo response;Self-assembly;β-Cyclodextrin;Gene delivery
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发布时间：2022-08-31 - 摘要：Polyethylene glycol monomer is an important monomer for the synthesis of functional polymer materials. The direct esterification method is one of the main methods for synthesizing such monomers, but the product prepared by this method has a low double bond retention rate. To solve this problem, in this study, Polyethylene glycol monomethyl ether-200 acrylate (MPEGA-200) with high yield and high double bond retention was synthesized by direct esterification of methoxy polyethylene glycol (MPEG-200) with acrylic acid (AA), and by introducing color-changing silica gel into the reaction system based on the presence of a water-carrying agent to enhance the water removal efficiency. FT-IR and 1H NMR were used to characterize MPEGA-200, and the biocompatibility of MPEGA-200 was evaluated by catalase activity analysis. The optimal conditions for synthesizing MPEGA-200 were determined by orthogonal experiments. The results shown that the optimal conditions are: n(MPEG-200)∶n(AA)=1∶2, the additions of inhibitor and catalyst were 2% (based on the total acid and alcohol mass), 18% of petroleum ether and 12% of color-changing silica gel, the reaction time was 6h, and the esterification temperature was 120℃. Under the conditions, 95.47% of esterification rate, 95.45% of double bond retention and 87.68% of yield can be reached. In addition, the influences of various factors on esterification were studied by the single factor method.关键词：Polyethylene glycol monomer;Methoxy polyethylene glycol-200;Direct esterification;Double bond retention rate;Biocompatibility
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发布时间：2022-08-31 - 摘要：Carbon nanotubes (CNTs) and liquid crystalline polymers have many similarities in the aspects of molecular structure and properties. These similarities enable carbon nanotube to be a typical case for the teaching of polymer physics. This paper focuses on the molecular structure, physical and mechanical properties, and the phase behavior of carbon nanotube solution by comparing with rigid-rod polymers. Furthermore, the application of liquid crystal spinning on the fabrication of highly oriented CNT fiber is further introduced, which refers to the manufacture process of Kevlar fiber. In addition, the characteristics of CNT fiber and organic fibers are compared. By optimizing the main line and content, this case teaching may raise consciousness of students' independent learning. Students’ innovative ability and initiative will be promoted by strengthening cross-disciplinary study. The case teaching may also help to enhance the teaching effect and improve teaching quality.关键词：Polymer physics;Carbon nanotube;Case;Teaching
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发布时间：2022-08-31 - 摘要：Glass transition is an important part of the polymer teaching. The change of free volume and the movement of molecular segments during the transformation process are difficult to understand for undergraduate students. Using a molecular simulation method on a computer to obtain a three-dimensional visualization, students can more intuitively observe changes in free volume and molecular chains. Refining the latest scientific research results of molecular simulation technology in the research of glass transition in recent years, We obtain the course materials with both theoretical basis and adaption of undergraduate teaching. The simulation experiments can obtain the data by ultra-fast temperature rise and fall that can not be achieved by the instrument test. And they were compared with the experimental data obtained by the instrument test, which verified a theory view. That expanded the scope of the experiment and achieved a good teaching effect.关键词：Glass transition;Molecular dynamics simulation;Polymer;Undergraduate experiment
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发布时间：2022-08-31 - 摘要：Magnesium hydroxidewas selected as the dispersant, Methacrylate was chosen as polymerization monomer for suspension polymerization. The effects of dispersants dosage, initiators, water and monomer ratio, stirring speed, reaction temperature and reaction time on polymeronization were studied. The experimental results show that the improved method has much more advantages compared with the suspension polymerization of polyvinyl alcohol(PVA) as dispersant in polymer experiment materials, such as easy to operate, the reaction time is less, the stability of the system is high. The good effect indicates that the improved experimental design can be used as the content of "polymer chemistry experiment for undergraduate students" .关键词：Methacrylate;Suspension polymerization;Improvement;Experimental teaching
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发布时间：2022-08-31 - 摘要：Surface and Interface of Materials is a distributional elective course for the composite-aspect of polymer material and engineering major. This course plays an important vanguard role in helping students to establish a solid foundation of subject and develop an interest in the composite-aspect. Aiming to "improve the charm of teaching and build a good course" , we fully implement the guiding ideology that the content of course is the foundation of the charm of teaching and that teaching methodology and teaching tools are catalysts which efficiently convert the content of course to the charm of teaching. According to the feedback, our reform measures have received wide recognitions from our students with respect to the improvements in teaching quality and learning efficiency.关键词：Surface and Interface of Materials;Teaching reform;Charm of Teaching;Good Course
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发布时间：2022-08-31 - 摘要：Production practice is an important part of practical training for polymer materials and engineering specialty. It plays a role of closely combining the learning content of theoretical courses with engineering practice. Based on the concept of OBE (Outcome Based Education), students are trained by engineers according to the requirements of enterprise, and more attentions are paid to the coordination of practical training between the university and the enterprise. At the same time, some problems encountered in practice are discussed, and some further solutions are proposed.关键词：OBE;Polymer material;Production practice
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发布时间：2022-08-31
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