Universality of Viscoelastic Phase Separation and its application to the material design

粘弹性相分离的普遍性及其在材料设计中的应用

基本信息

批准号：
08455007
负责人：
TANAKA Hajime
金额：
$ 5.25万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

We have improved a general model of phase separation in isotropic condensed matter, namely, a viscoelastic model. We propose that the bulk mechanical relaxation modulus that has so far been ignored in previous theories plays an important role in viscoelastic phase separation in addition to the shear relaxation modulus. In polymer solutions, for example, attractive interactions between polymers under a poor-solvent condition likely cause transient gel-like behavior, which makes both bulk and shear modes active. Although such attractive interaction between molecules of the same component exist universally in the two phase region of a mexture, the stress arising from attractive interactions is asymmetrically diveded between the components only in dynamically asymmetric mixtures such as polymer solutions and colloidal suspensions. Thus the interaction network between the slower components, which can store the elastic energy against its deformation through bulk and shear moduli, is formed. This unique feature originates from the difference in mobility between two components of a mixture. It is the bulk relaxation modulus associates with this interaction network that is primarily responsible for the appearance of the sponge structure to viscoelastic phase separation and the phase inversion. It suppresses short-wavelength concentration fluctuation in the initial stage, and causes the volume shirinking of a more viscoelastic phase. We also propose a simple general law of stress division between the two components of a mixture, as a straightforward extension including this new effect is a general model that can describe all types of isotropic phase separation. The physical origin of volume shrinking behavior during viscoelastic phase separation and the universality of the resulting sponge like structure are also discussed.

我们改善了各向同性冷凝物质中相位分离的一般模型，即粘弹性模型。我们建议，除了剪切弛豫模量外，迄今为止在先前理论中忽略的大机械弛豫模量在粘弹相分离中起着重要作用。例如，在聚合物溶液中，在溶剂疾病较差的条件下聚合物之间的有吸引力的相互作用可能会导致瞬态凝胶样行为，从而使散装模式和剪切模式都活跃。尽管同一组分分子之间的这种吸引人的相互作用普遍存在于Mexture的两个相区域中，但吸引人相互作用引起的应力仅在组分之间仅在动态不对称混合物（例如聚合物溶液）和胶体悬浮液中进行不对称。因此，形成了较慢的组件之间的相互作用网络，该组件可以通过散装和剪切模量来存储弹性能量的变形。这种独特的特征源于混合物的两个组成部分之间的迁移率差异。它是与这种相互作用网络的大量弛豫模量，主要负责海绵结构与粘弹性相分离和相位反转的外观。它在初始阶段抑制了短波浓度的波动，并导致粘弹性相的体积。我们还提出了混合物的两个组成部分之间的简单应力划分法则，因为包括这种新效果的直接扩展是一个通用模型，可以描述所有类型的各种各型各向同性相分离。还讨论了粘弹性相分离和所得海绵类似结构的普遍性期间体积缩小行为的物理起源。