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EFFECTS OF DEFORMATION-INDUCED ORIENTATION ON CYCLIZATION AND OXIDATION OF POLYACRYLONITRILE fiberS DURING STABILIZATION PROCESS

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Chinese Journal of Polymer Science 2012年第6期30卷 786-795页

作者：刘杰 Key laboratory of carbon fiber and functional polymers Ministry of EducationBeijing University of Chemical Technology

Orientation of copolymer polyacrylonitrile （PAN） chains during their deformation prior to stabilization and the further effect on the stabilization were investigated in detail. Results reveal that the orientation of PAN chains presents a saturation point of 69.51% when the deformation ratio reaches approximately 1.07, meanwhile the cyclization rather than the oxidation has a stronger dependence on the orientation of PAN chains during stabilization. The cyclization is facilitated that the cyclization degree is increasing while the activation energy is decreasing obviously as a consequence of the developing orientation of PAN fibers before the saturation point; however, it is restrained during the further deformation of PAN fibers after the point. The resulting carbon fibers obtained from the PAN fibers prepared at the saturation point possess the highest mechanical properties of 4.07 GPa in tensile strength and 249.0 GPa in tensile modulus.

关键词： Polyacrylonitrile Orientation Deformation Stabilization carbon fiber.

SYNTHESIS OF POLY(GLUTAMIC ACID-co-ASPARTIC ACID) VIA COMBINATION OF N-CARBOXYANHYDRIDE RING OPENING POLYMERIZATION WITH DEBENZYLATION

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Chinese Journal of Polymer Science 2013年第12期31卷 1706-1716页

作者： Wei-xi Yang Ling-ling Wang Han Zhu Ri-wei Xu 吴一弦 State Key laboratory of Chemical Resource Key Laboratory of Carbon Fiber and Functional Polymers(Ministry of Education)Beijing University of Chemical Technology

The random copolymers of glutamic acid （LG） and aspartic acid （ASP）, poly（LG-co-ASP）, with designed compositions could be successfully synthesized via combination of N-carboxyanhydride ring opening copolymerization with debenzylation. Ring opening copolymerizations of y：benzyl-L-glutamate N-carboxyanhydride （BLG-NCA） and β-benzyl-Laspartate N-carboxyanhydride （BLA-NCA） were carried out by using different amines including triethylamine （TEA）, diethylamine, n-hexylamine （NHA）, triphenylamine, diphenylamine or aniline as initiators. All the 6 amines were highly efficient to get well-defined poly（BLG-co-BLA） copolymers with designed compositions although the polymerizations proceeded via different mechanisms （normal amine mechanism or/and activated monomer mechanism）, which are based on chemical structure of amines. The molecular weights of poly（BLG-co-BLA） copolymers could be mediated by both TEA concentration and polymerization time. Then, debenzylation ofpoly（BLG-co-BLA） copolymers was conducted to prepare the corresponding hydrophilic random eopolymers of poly（LG-co-ASP） with a-subunit structure in ASP structural units. The contents of LG structural units in poly（LG-co-ASP） copolymers matched with those of BLG-NCA in NCA-monomer feeds in ring opening copolymerizations initiated by NHA or TEA and were closed to the theoretical line. The diblock copolymer of poly（BLG-b-BLA） could also be synthesized via living NCA ring opening copolymerization by sequential addition of BLG- NCA and BLA-NCA.

关键词： Peptide Ring opening polymerization Copolymer Glutamic acid Aspartic acid.

HIGH IMMOBILIZATION OF ANTIBACTERIAL MOIETIES ONTO MONODISPERSE MICROSPHERES BY DISPERSION POLYMERIZATION USING BICATIONIC VIOLOGEN SURFMER

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Chinese Journal of Polymer Science 2012年第6期30卷 865-872页

作者：刘莲英杨万泰 Key laboratory of carbon fiber and functional polymers Ministry of EducationCollege of Materials Science and EngineeringBeijing University of Chemical Technology

In order to achieve monodisperse particles with high content of antibacterial groups covalently bonded on surface, a bicationie viologen, N-hexyl-N-（4-vinylbenzyl）-4,4＇-bipyridinium bromide chloride （HVV） was devised as a surfrner in dispersion polymerization of styrene （St） using a mixture of methanol （or ethylene glycol） and water as media. Effects of content of HVV, its addition profile and composition of reaction media on particles size and incorporation of HVV moieties were mainly investigated. The attachment of silver and gold nanoparticles on particle surface under UV irradiation ascertained the surface-bonded HVV segments. SEM, TEM observations and XPS, zata potential measurements indicated that increase of initial HVV contents and addition of HVV （when polymerization had been performed for 3 h） led to grown particles and enhanced immobilization of HVV moieties. Using a mixture of ethylene glycol and water as reaction media, small particles （520-142 nm） with highly attached HVV moieties were prepared. Furthermore, antibacterial efficacy of the resultant particles against S. aureus was assayed, and particles with more HVV moieties anchored on surface demonstrated greater efficiency of antibacterial activity.

关键词： Antibacterial microsphere Monodispersity Dispersion polymerization Viologen Surfmer.

Self-healing Supramolecular Polymer Composites by Hydrogen Bonding Interactions between Hyperbranched Polymer and Graphene Oxide

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Chinese Journal of Polymer Science 2018年第5期36卷 584-591页

作者： Yi-Gang Luan Xiao-A Zhang Sheng-Ling Jiang Jian-Huan Chen Ya-Fei Lyu Key laboratory of carbon fiber and functional polymers of Ministry of Education College of Materials Science and Engineering Beijing University of Chemical Technology

A self-healing supramolecular polymer composite（HSP-GO） was designed and prepared via incorporation of modified graphene oxide to hyperbranched polymer by hydrogen-bonding interactions. The polymer matrix based on amino-terminated hyperbranched polymer（HSP-NH_2） was synthesized by carboxylation, Curtius rearrangement, and amination of hydroxyl-terminated hyperbranched polyester（HP-OH）, while the modified graphene oxide was prepared by transformation of hydroxyl to isocyanate and further to carbamate ester. Spectroscopic methods were utilized to characterize the obtained polymer composites. Stress-strain test was selected to carefully study the self-healing property of HSP-GO. It is found that a small amount of modified graphene oxide（up to 2 wt%） improves the glass transition temperature（T_g）, tensile strength, Young＇s modulus, and self-healing efficiency of the polymer composites. After healed at room temperature for 10 min, the addition of modified graphene oxide improves the self-healing efficiency to 37% of its original tensile strength. The experiment result shows that the self-healing efficiency is related to the density of hydrogen bonding site and the molecular movement.

关键词： Self-healing Supramolecular polymer Graphene oxide Hydrogen bonding

HYPERBRANCHED EPOXY RESINS PREPARED BY PROTON TRANSFER POLYMERIZATION FROM AN A_2 + B_3 SYSTEM

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Chinese Journal of Polymer Science 2011年第3期29卷 300-307页

作者：李效玉 Key laboratory of carbon fiber and functional polymers Ministry of Education College of Materials Science and EngineeringBeijing University of Chemical Technology

Epoxy-terminated hyperbranched polymers （EHBPs） were prepared by proton transfer polymerization and characterized by FT-IR, 1H-NMR and GPC. The solution and thermal properties of the uncured samples and mechanical properties of cured samples were examined. The thermo-stable products had good solubility in polar solvents, low solution viscosity and Tgs ranging from 15℃ to 33℃ depending on their molecular weights. The mechanical properties of cured films were studied and compared with those of a bisphenol-A type epoxy resin. The films of EHBPs had good impact resistance and high gloss values without sacrificing hardness and adhesion.

关键词： Hyperbranched Epoxy Proton transfer polymerization.

Synthesis and Characterization of Carborane Bisphenol Resol Phenolic Resins with Ultrahigh Char Yield

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Chinese Journal of Polymer Science 2015年第11期33卷 1606-1617页

作者： Shi-cheng Qi Guo Han Hong-rui Wang Ning Li 张孝阿 Sheng-ling Jiang Ya-fei Lu College of Materials Science and Engineering Key Laboratory of Carbon Fiber and Functional Polymers of Ministry of Education Beijing University of Chemical Technology

Two carborane-containing resol phenolic resins（P1 and P2） with high boron content were synthesized via the reaction of carborane bisphenols（1 and 2） with formaldehyde in the presence of alkaline. HRMS results indicate that P1 is mainly composed of hydroxymethylated o-carborane bisphenols, the Mw of which was restrained around 500 due to the strong steric hindrance of o-carborane bisphenol. In contrast, the molecular weight of P2 was well regulated under various reaction conditions. The obtained resins were characterized with spectroscopic techniques including FTIR, 1H-NMR, ^13C-NMR, and 11B-NMR, which gave satisfactory results. TGA studies show that P2 shows char yield of 88.9% and 92.9% at 900 ℃ under nitrogen and air respectively. The imported carborane cage endows phenolic resin with ultrahigh char yield. Particularly, the char yield of the obtained carborane-containing phenolic resin under air is higher than that under nitrogen. FTIR and XRD confirm that the carborane cage could react with oxygen to form B2O3 at elevated temperatures, which postpones the thermal decomposition of phenolic resin and accounts for the high char yield.

关键词： Carborane-containing resol phenolic resin High boron content Char yield

Enhanced Crystallization Rate of Biodegradable Poly(ε-caprolactone) by Cyanuric Acid as an Efficient Nucleating Agent

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Chinese Journal of Polymer Science 2017年第12期35卷 1517-1523页

作者： Kang-jing Zhang 邱兆斌 State Key laboratory of Chemical Resource Engineering Ministry of Education Key Laboratory of Carbon Fiber and Functional Polymers Beijing University of Chemical Technology

The influence of cyanuric acid（CA） as an efficient nucleating agent on the crystallization behavior and morphology of biodegradable poly（ε-caprolactone）（PCL） was extensively studied in this work with several techniques for the first time. The nonisothermal melt crystallization behavior and overall isothermal melt crystallization rate of PCL were significantly enhanced by only a small amount of CA. The addition of CA apparently improved the nonisothermal melt crystallization peak temperature, overall isothermal melt crystallization rate, and nucleation density of PCL spherulites, but did not modify the crystallization mechanism and crystal structure of PCL, indicating that CA was an efficient nucleating agent for the crystallization of PCL. The possible nucleation mechanism of CA on the crystallization of PCL was also discussed on the basis of their crystal structures.

关键词： Biodegradable Crystallization behavior Poly(ε-caprolactone) Cyanuric acid Nucleating agent

Crystalline Morphology and Crystallization Kinetics of Melt-miscible Crystalline/Crystalline Polymer Blends of Poly(vinylidene fluoride) and Poly(butylene succinate-co-24mol% hexamethylene succinate)

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Chinese Journal of Polymer Science 2014年第9期32卷 1139-1148页

作者： Gu-yu Wang 邱兆斌 State Key laboratory of Chemical Resource Engineering Key Laboratory of Carbon Fiber and Functional PolymersMinistry of Education Beijing University of Chemical Technology

Poly（vinylidene fluoride）（PVDF） and poly（butylene succinate-co-24 mol% hexamethylene succinate）（PBHS）, both crystalline polymers, formed melt-miscible crystalline/crystalline polymer blends. Both the characteristic diffraction peaks and nonisothermal melt crystallization peak of each component were found in the blends, indicating that PVDF and PBHS crystallized separately. The crystalline morphology and crystallization kinetics of each component were studied under different crystallization conditions for the PVDF/PBHS blends. Both the spherulitic growth rates and overall isothermal melt crystallization rates of blended PVDF decreased with increasing the PBHS composition and were lower than those of neat PVDF, when the crystallization temperature was above the melting point of PBHS component. The crystallization mechanism of neat and blended PVDF remained unchanged, despite changes of blend composition and crystallization temperature. The crystallization kinetics and crystalline morphology of neat and blended PBHS were further studied, when the crystallization temperature was below the melting point of PBHS component. Relative to neat PBHS, the overall crystallization rates of the blended PBHS first increased and then decreased with increasing the PVDF content in the blends, indicating that the preexisting PVDF crystals may show different effects on the nucleation and crystal growth of PBHS component in the crystalline/crystalline polymer blends.

关键词： Crystalline morphology Crystallization kinetics Polymer blends.

Real-time Monitoring of Living Cationic Ring-opening Polymerization of THF and Direct Prediction of Equilibrium Molecular Weight of Poly THF

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Chinese Journal of Polymer Science 2015年第1期33卷 23-35页

作者： An-ru Guo Fan Yang Rui Yu 吴一弦 State Key laboratory of Chemical Resource Engineering Key Laboratory of Carbon Fiber and Functional Polymers(Ministry of Education) Beijing University of Chemical Technology

A convenient real-time monitoring of monomer concentration during living cationic ring-opening polymerizations of tetrahydrofuran（THF） initiated with methyl triflate（Me OTf） has been developed for kinetic investigation and determination of equilibrium monomer concentration（[M]e） via in situ FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance（ATR） immersion probe. The polymerization rate was first order with respect to monomer concentration and initiator concentration from the linear slope of ln（[M]0-[M]e）/（[M]-[M]e） versus polymerization time at different temperatures in various solvents. [M]e decreased linearly with initial monomer concentration while increased exponentially with increasing polymerization temperature. The equilibrium also strongly depends on solvent polarity and its interaction with monomer. The equilibrium polymerization time（te） decreased with increasing solvent polarity and decreased linearly with increasing [M]0 in three solvents with different slopes to the same point of bulk polymerization in the absence of solvent. Equation of Mn,e = 72.1/（0.14–0.04[M]e） has been established to provide a simple and effective approach for the prediction for the number-average molecular weight of poly THFs at equilibrium state（Mn,e） in the equilibrium living cationic ring-opening polymerization of THF at 0 °C.

关键词： Cationic ring-opening polymerization Living polymerization Tetrahydrofuran Equilibrium Kinetics.