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Study of Volume Phase Transition of Polymer Gel from the Mesoscopic Region

从介观区域研究聚合物凝胶的体积相变

基本信息

批准号：
12640383
负责人：
KUBOTA Kenji
金额：
$ 2.18万
依托单位：
Gunma University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

This research project was planned to study the physicochemical characteristics and volume phase transition of polymer gel from the mesoscale region with regard to the inhomogeneity inside the gel. Thermal response of gel beads of PNiPAM and PNnPAM were studied mainly. In order to characterize such a thermal response relating to the size effect, we tried to obtain the monodisperse gel beads with micron size by various synthesizing methods, and various important findings relating to the volume phase transition were obtained. In case of micron size copolymerized gel with acrylic acid, symmetric gel beads at the swelling state shrink to asymmetric shape at high temperature. This results from that the gel, which grows sufficiently upto such a size, contains inhomogeneous network structure and this causes asymmetric shrinkage. This means the importance of studying the detailed network structure in the mesoscale. Moreover, by the ultrasonic velocity of gel beads suspension, the variation of the number of hydrated water molecules in the course of volume phase transition was able to be evaluated, and is in fairly good agreement with the theoretical prediction. In order to observe the gel network in real space, confocal laser scanning microscopy was applied to the biological gel of fibrin, and we succeeded to clarify the backbone of gel network and obtained the fractal dimension. The obtained dimensions were in good agreement with the results determined by the dynamic light scattering measurements. Thus, the importance of detailed characterization of mesoscopic structure of gels was clarified.

本研究计划从介观尺度研究聚合物凝胶的物理化学特性和体积相变，考虑凝胶内部的不均匀性。主要研究了PNiPAM和PNnPAM凝胶球的热响应性。为了表征这种与尺寸效应相关的热响应，我们尝试通过各种合成方法获得微米级的单分散凝胶珠，并获得了与体积相变相关的各种重要发现。在微米级共聚凝胶与丙烯酸的情况下，在溶胀状态下的对称凝胶珠在高温下收缩为不对称形状。这是由于充分生长到这种尺寸的凝胶含有不均匀的网络结构，这导致不对称收缩。这意味着在中尺度上研究详细的网络结构的重要性。此外，通过凝胶珠悬浮液的超声速度，可以评价体积相变过程中水合水分子数的变化，与理论预测相符合较好。为了在真实的空间观察凝胶网络，将激光共聚焦扫描显微镜应用于纤维蛋白生物凝胶，成功地阐明了凝胶网络的骨架，并获得了分形维数。所获得的尺寸与动态光散射测量确定的结果吻合良好。从而阐明了详细表征凝胶介观结构的重要性。