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Structure of Polymer Gels Controlled by Phase Separation

相分离控制的聚合物凝胶结构

基本信息

批准号：
07651107
负责人：
KANAYA Toshiji
金额：
$ 1.34万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07651107/
关键词：
poly (vinyl alcohol)polymer gels phase separation gelation process small angle neutron scattering light scattering

项目摘要

We have studied structure of poly (vinyl alchol) (PVA) gels and its formation process after quenching from homogeneous solutions at a high temperature (100ﾟC) using time resolved light and small angel neutron scattering techniques.In the light scattering measurements at 23ﾟC,it was clearly observed that the scattering intensity profile shows a broad peak at Q (length of scattering vector) =5*10^<-4> *^<-1>. The peak position is independent of time while intensity increases exponentially with time, suggesting that spinodal decomposition-like phase separation occurs in the PVA gels at 23ﾟC.On the other hand, no peak is observed in the scattering profile after quenching to -40ﾟC from a high temperature (100ﾟC). This means that in the PVA gels formed at low temperatures, phase separation dose not occurs and the gels are rather homogeneous.On the basis of the small angle neutron scattering measurements, we elucidated structure of the network of the gels and its formation process. It was found that the cross-linking points are crystallite with radius of about 70* and the average distance between crystallites is about 200*.From both the light and neutron scattering experiments, we concluded that the final structure of the PVA gels are determined by competition between the rate of crystallite formation and the rate of the phase separation. By controlling the two rates, it would be possible to control the structure of PVA gel.

用时间分辨光和小角中子散射技术研究了聚乙烯醇(PVA)凝胶的结构及其在高温(100ﾟC)下从均相溶液中猝灭后的形成过程.在23ﾟC的光散射测量中，清楚地观察到在Q(散射矢量长度)=5*10^&lt；-4&gt；*^&lt；-1&gt；处有一个宽峰.峰的位置与时间无关，而强度随时间呈指数增加，表明在23ﾟC下，PVA凝胶中发生了调幅分解样的相分离。另一方面，从高温(100ﾟC)猝灭到-40ﾟC后，没有观察到峰。这意味着在低温下形成的PVA凝胶中没有发生相分离，凝胶是比较均匀的。在小角中子散射测量的基础上，我们阐明了凝胶网络结构及其形成过程。结果表明，PVA凝胶的交联点为半径约为70*的微晶，微晶间的平均距离约为200*。光散射和中子散射实验表明，凝胶的最终结构是由微晶形成速率和相分离速率之间的竞争决定的。通过控制这两种速率，可以控制PVA凝胶的结构。