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.

该项目计划从可以统一理解聚合物溶液的凝胶与相变或相位分离的动力学的角度研究渗透模型的有效性。我们研究了对聚合物溶液凝胶化的追踪和成长簇的凝胶化，聚合物分子的表征，其凝胶表现出独特的相行为，以及对相变的多分散性效应。我们主要使用光散射，并分析了相关函数的衰减速率分布。为了量化反应程度，还研究了辐射诱导的聚合和凝胶化系统。对于在非常稀释的条件下发生凝胶化的多糖，在簇强度和大小中检测到异常，并证明可以服从幂律。对于辐射引起的凝胶，很难准确确定凝胶点。相关函数显示凝胶点的幂律行为，多糖和辐射诱导的凝胶的指数约为0.6-0.7，显示与化学凝胶有很大的差异。物理凝胶和化学凝胶之间存在质的差异。可以确定，非连通性的程度与凝胶化密切相关。观察到了相位分离（分离增长）和胶凝之间的耦合的有趣现象。对于表现出溶胶 - 凝胶过渡和体积相变的聚合物，进行了分子表征，并获得了这种独特的相行为的分子水平的碱基。特别是，阐明了不连续体积相变的起源。