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

研究结果概述在实验方面，详细研究了凝胶过渡区中的区域边界行为，以及在混合溶剂中嵌入的凝胶中特殊细胞图案的形成。另一方面，在理论方面，根据实验数据和唯象的考虑，分析了凝胶水在体积相变时的行为。(1)实现三相平衡和磁区边界的温度行为。由于需要更高的显微镜放大率来观察磁区的详细行为，因此可以快速而精确地测量磁区边界的运动。由于必须使用工作距离较小的物镜，因此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一困难。这项实验已经证实，更先进的…要全面了解凝胶的体积相变，需要更多的理论考虑。(2)凝胶相分离时特殊的细胞模式的观察。首次证明，当N-异丙基丙烯酰胺凝胶外的溶剂从纯水变为水-乙醇混合物时，产生了特征的细胞模式。构成这种图案的纤维被发现是双折射的，这表明聚集体具有某种结晶顺序。(3)凝胶水在体积相变时的行为。从今年的研究中得出的一个最重要的结果是，实际的体积相变发生的方式与由Covenona Flory理论预测的模型完全不同。结合目前所积累的各种实验事实，证明凝胶的收缩相不含自由水，并且存在某种由结合水分子和高分子链组成的有序结构。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系统。较少

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