Molecular Studies on Polymer Gels

用小角中子散射(SANS)、粘度计、强迫瑞利散射(FRS)、荧光退偏法和超声光谱分析等方法研究了聚合物凝胶的结构、凝胶转变行为和动力学特性。通过生成双峰网络研究了聚合物凝胶的拓扑特征。聚乙烯醇(PVA)溶液的SANS由分维为D的分形图的广义Zimm图估算出关联长度Xi。Xi随温度的变化呈现凝胶-溶胶转变。不同温度下凝胶的散射强度函数可以通过采用约化变量I(Q)/CXI^3和XQ来叠加，其中C和Q分别是单体浓度和散射矢量的大小。PVA-硼酸盐络合物在水溶液中的相行为和溶胶凝胶转变在给定的PVA浓度和离子强度的组合下，体系经历了明显的不透明…随着硼酸浓度的增加，转变更加明显。聚合物溶液的热可逆凝胶化动力学以聚(甲基丙烯酸丁酯)(PnBNA)、聚(甲基丙烯酸异丁酯)(PiBMA)、聚(甲基丙烯酸叔丁酯)(PtBMA)和聚(甲基丙烯酸异羟乙酯)(PHEMA)在异丙醇和异丁醇中的溶液为样品。聚甲基丙烯酸丁酯/异丙醇溶液的热可逆凝胶化机理强烈地依赖于其异构体的化学结构。研究还发现，聚苯乙烯(PS)和聚(2-氯苯乙烯)(P2CS)二元混合物中聚苯乙烯(PS)链的化学凝胶化所产生的弹性能修正了PS/P2CS混合物的浓度波动。模拟网络显示了许多网络缺陷的存在，如不满意的交联剂(扩链剂)、隔离链、未反应的交联剂和悬挂链。结果发现，模拟的链条再现了真实弹性体的几个拓扑特征。较少

Structure, solgel transition behavior, and dynamic aspects of polymer gels were investigated in terms of small angle neutron scattering (SANS), viscometry, forced Rayleigh scattering (FRS), fluorescence depolarization methods, and ultrasonic spectrosopy. Topological features of polymer gels were also studied by generating bimodal networks.SANS of poly (vinyl alcohol) (PVA) solutionsThe correlation length, xi, was estimated from a generalized Zimm plot for fractals having the fractal dimension of D. The variation of xi with temperature showed a gel-to-sol transition. The scattered intensity functions for the gels at different temperatures could be superimposed by employing reduced variables, I(q)/Cxi^3 and xiq, where C and q are the monomer concentration and the magnitude of the scattering vector, respectively.Phase behavior and solgel transition of PVA-borate complex in aqueous solutionsAt a given combination of PVA concentration and ionic strength, the system underwent a clear-opaque- … More clear transition with increasing boric acid concentration. This behavior was explained by a balance of the exclude volume effect due to intra- and inter-chain crosslinks and electrostatic potentials.Dynamical aspects of thermoreversible gelation of polymer solutionsSolutions of poly (n-butyl methacrylate) (PnBNA), poly (isobutyl methacrylate) (PiBMA), poly (tert-butyl methacrylate) (PtBMA) and poly (2-hydroxyethyl methacrylate) (PHEMA) in 2-propanol and 2-butanol were used as samples. The thermoreversible gelation mechanism of poly (butyl methacrylate)/2-propanol solutions strongly depends on the chemical structures of their isomers. It was also found that the elastic energy that is generated by the chemical gelation of polystyrene (PS) chains in a binary mixture of PS and poly (2-chlorostyrene) (P2CS), modifies the concentration fluctuations of PS/P2CS mixtures.Bimodal Polymer NetworksComputer simulations were performed on two and three dimensional square lattices with tetrafunctional crosslinks. The simulated networks demonstrated the presence of appreaciable of number of network imperfections, such as unsatisfied crosslinks (chain extenders), isolated chains, unreacted crosslink agents, and dangling chains. It was found that the simulated chains re-produced several topological features of real elastomers. Less