Kinetics of structural transitions in polymeric systems ・・・properties of gyroid structure・・・

长谷川小组合作研究嵌段共聚物，Imai小组合作研究水与表面活性剂的混合物，Ohta-Nonomura小组进行理论研究。Ohta和Nonomura研究了软物质的特征之一回转结构的形成和稳定性的基本性质，应用模展开法和计算机模拟发现，Fddd结构和普通介观结构一样是稳定的热平衡结构，而穿孔层片结构是亚稳态结构。还发现在陀螺体结构向片层结构转变的过程中也出现了Fddd结构，此时陀螺体的立方对称性被破坏。强调这些理论预测与长谷川小组的实验是一致的，后者进行了X射线散射，发现了从片状结构、Fddd结构和回旋结构的一系列形态转变。IMAi基团的实验表明，水/表面活性剂体系的转变动力学与嵌段共聚物的转变动力学有很大不同。因此，我们需要进一步的理论和实验研究来阐明软物质动力学的普遍特征。

A cooperative research was carried out on block copolymers by Hasegawa group, on water and surfactant mixtures by Imai group and the theoretical investigation by Ohta-Nonomura group. Ohta and Nonomura studied the fundamental properties of the formation and the stability of the gyroid structure which is one of the characteristic features of soft matter.They applied the mode expansion method and computer simulations and found that Fddd structure as well as the ordinary mesoscopic structures is a stable thermal equilibrium structure whereas perforated lamellar structure is metastable. It was also found that Fddd structure appears also in the course of the transitions between gyroid structure and lamellar structure where the cubic symmetry of gyroid is broken. It is emphasized that these theoretical predictions are consistent with the experiments of Hasegawa group who carried out X-ray scattering and found a series of morphological transitions from lamellar, Fddd and gyroid structures. The experiments of Imai group showed that the transition kinetics in water/surfactant systems are quite different from those of block copolymers. Therefore, we need further theoretical and experimental investigations to clarify the universal features of the dynamics of soft matter.