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Gelation of Polymer Solution and Percolation Model

聚合物溶液的凝胶化和渗滤模型

基本信息

批准号：
08454109
负责人：
KUBOTA Kenji
金额：
$ 3.26万
依托单位：
Gunma University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

This project was planned to study the validity of percolation model from the viewpoint that the gelation of polymer solution can be understood unifiedly together with the dynamics of phase transition or phase separation. We carried out the study of tracing to gelation of polymer solution and chracterization of growing clusters, characterization of polymer molecules the gel of which exhibits unique phase behavior, and polydispersity effect to phase transition. We used light scattering mainly and analyzed the decay rate distribution of the correlation functions. In order to evluate the degree of reaction quantitatively, radiation-induced polymerization and gelation system was also studied. For polysaccharide where gelation occurs at very dilute condition, anomaly was detected in cluster intensity and size, and it was shown to obey the power-law. For radiation-induced gel, it was difficult to determine the gelation point accurately. Correlation function shows power-law behavior at the gelation point, and the exponents for polysaccharide and radiation-induced gel were about 0.6-0.7 showing a big difference from the chemical gel. There exists a qualitative difference between physical and chemical gel. It was ascertained that the extent of nonergodicity is correlated strongly with the gelation. Interesting phenomena for the coupling between the phase separation (uncleation-growth) and the gelation was observed. For the polymers which exhibit sol-gel transition and volume phase transition, molecular characterization was carried out and the bases at the molecular level for such unique phase behavior were obtained. Especially, the origin of discontinuous volume phase transition was clarified.

该项目计划从聚合物溶液的凝胶化与相变或相分离动力学统一理解的角度来研究渗流模型的有效性。我们开展了聚合物溶液凝胶化的追踪和生长团簇的表征、凝胶表现出独特相行为的聚合物分子的表征以及相变的多分散效应的研究。我们主要利用光散射来分析相关函数的衰减率分布。为了定量评价反应程度，还对辐射诱导聚合和凝胶体系进行了研究。对于在非常稀的条件下发生凝胶化的多糖，在簇强度和大小方面检测到异常，并且表明它服从幂律。对于辐射诱导凝胶，很难准确确定凝胶点。相关函数在胶凝点呈幂律行为，多糖和辐射凝胶的指数约为0.6-0.7，与化学凝胶有很大差异。物理凝胶和化学凝胶之间存在质的差异。已确定非遍历性的程度与凝胶化密切相关。观察到相分离（解核生长）和凝胶化之间的耦合的有趣现象。对于表现出溶胶-凝胶转变和体积相变的聚合物，进行了分子表征，并获得了这种独特相行为的分子水平基础。特别是，阐明了不连续体积相变的起源。