Dynamics of Morphology Transition of Complex Liquids

本研究项目的目标是揭示复杂液体(软物质)中形态转变的动力学。为此，我们调查了以下三个系统。表面活性剂/水体系和嵌段共聚物的有序-有序转变。在有序-有序转变之前，观察到特征的涨落模式。其使目标有序相通过亚稳定中间相。金茨堡-朗道方案很好地描述了这种行为。此外，我们还发展了一种模式展开理论，揭示了有序-有序转变的动力学路径。棒状颗粒聚合物体系的形态转变：在棒状颗粒悬浮液中加入聚合物会引起各向同性到向列相的转变。这一现象是由平移熵和混合熵(耗尽相互作用)的比较引起的。我们发现，由于大的排斥体效应，半刚性聚合物广泛地增强了耗尽相互作用(^~10^&lt；3-4&gt；)，蒙特卡罗模拟再现了观察到的现象与链的刚性的关系。膜聚合物体系的形态转变。利用微乳液液滴相，我们可以将聚合物链限制在一个纳米级的封闭球形容器中。由于限制导致的高分子链的熵损失带来了形态转变，以最小化由链的构象熵和膜的弹性能组成的总自由能。

The target of this research project is to reveal dynamics of morphology transitions in complex liquids (soft matter). For this purpose we investigated the following three systems.1. Order-order transition of surfactant/water systems and block copolymers.Characteristic fluctuation modes are observed prior to an order-order transition. Which brings the destination ordered phase through a meta stable intermediate phase. This behavior is well described by the Gintzburg-Landau scheme. Furthermore we developed a mode expansion theory, which reveals the kinetic pathway of the order-order transition.2. Morphology transition of rod partical + polymer system.Addition of polymer to the rod particle suspension brings isotropic to nematic transition. This phenomenon is induced by compentition between translational entropy and mixing entropy(depletion interaction). We found that the semi-rigid polymer enhances the depletion interaction extensively (^~10^<3-4>) due to the large excluded volume effect.The Monte-Carlo simulation reproduces the observed phenomenon as a function of the chain rigidity.3. Morphology transition of membrane + polymer system.Using microemulsion droplet phase, we can confine polymer chains into a nano-scale closed spherical container. The entropy loss of the polymer chain due to the confinement brings morphology transition in order to minimize the total free energy consisting of conformational entropy of the chain and elastic energy of the membrane.