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STABILITY OF THE TWO-PHASE COEXISTENCE AND THE STRUCTURE OF PHASE BOUNDARIES NEAR THE FIRST-ORDER PHASE TRANSITION

两相共存的稳定性和一阶相变附近的相界结构

基本信息

批准号：
05640437
负责人：
HIROTSU Shunsuke
金额：
$ 1.34万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05640437/
关键词：
Polymer gels Phase transition Phase equilibria Domein boundary Phase separation Gel water Viscoelasticity Coherent solid ゲル体積相転移分域構造高分子物理学相境界パターン形成 2相共存領域

项目摘要

Summary of Research ResultsOn the experimental side, the behavior of domain boundaries in a transition region of gels, and formation of peculiar cellular patterns inside gels embedded in a mixed solvent have been investigated in detail. On the theoretical side, on the other hand, behavior of gel water at the volume phase transition has been analyzed in terms of the experimental data and the phenomenological considerations.(1)Realization of the tri-phasic equilibrium and the temperature behavior of domain boundaries.Fast and precise measurements of the movement of domain boundaries were made possible by requires higher magnification of a microscope to observe the detailed behavior of the domain. Because an objective lense of smaller working distance had to be used, temperature regulation of the sample had become more difficult. We overcame this difficulty by improving the temperature controller as well as the sample holder. It has been confirmed by this experiment that the more advanced … More theoretical considerations than the previous phenomenological one is needed to understand fully the volume phase transition of gels.(2)Observation of the peculiar cellular pattern at the phase separation of gels.It was first demonstrated that, a characteristic cellular pattern developls when the solvent outside the N-isopropylacrylamide gel is changed from pure water to water-ethanol mixture. The fibers constituting this pattern have been found to be birefringent, which suggests that the aggregates has some sort of crystalline order. It is also deduced that NIPA chains are fairly rigid.(3)Behavior of gel water at the volume phase transition.A most significant result emerged from this year's study is that the real volume phase transition occurs in a fairly different fashion from the model predicted by the coventiona Flory's theory. Combining various experimental facts accumulated so far, it has become evident that the shrunken phase of gel does not contain free water, and some kind of ordered structure is present, which is made up from bound water molecules and polymer chains. This fact is important because even a gel made from homopolymer and pure water has some kind of secondary or tertially structure, and thus can be regarded as a model system of much more complex biopolymer systems. Less

摘要的研究结果在实验方面，域边界的行为在过渡区的凝胶，并形成独特的细胞模式内的凝胶嵌入在混合溶剂中进行了详细的研究。在理论方面，另一方面，凝胶水在体积相变的行为进行了分析的实验数据和唯象的考虑。（1）三相平衡的实现和畴界的温度行为通过提高显微镜的放大倍数来观察畴界的详细行为，使得快速、精确地测量畴界的运动成为可能。由于必须使用工作距离较小的物镜，样品的温度调节变得更加困难。我们通过改进温度控制器和样品保持器克服了这个困难。这个实验已经证实， ...更多信息理论上的考虑比以前的唯象的一个需要充分理解凝胶的体积相变。（2）凝胶相分离时特殊胞状结构的观察首次证明，当N-异丙基丙烯酰胺凝胶外的溶剂由纯水变为水-乙醇混合物时，出现了一种特殊的胞状结构。已经发现构成这种图案的纤维是双折射的，这表明聚集体具有某种晶体有序性。还推断NIPA链是相当刚性的。（3）凝胶水在体积相变时的行为今年的研究中出现的一个最有意义的结果是，真实的体积相变以与常规Flory理论预测的模型相当不同的方式发生。结合迄今为止积累的各种实验事实，可以看出，凝胶的收缩相不含自由水，而是存在某种有序结构，它由结合水分子和聚合物链组成。这一事实很重要，因为即使是由均聚物和纯水制成的凝胶也具有某种二级或三级结构，因此可以被视为更复杂的生物聚合物体系的模型体系。少