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Study on the Coupling of Mutual Diffusion to Viscoelasticity in Polymer Solutions

聚合物溶液中相互扩散与粘弹性的耦合研究

基本信息

批准号：
11450368
负责人：
EINAGA Yoshiyuki
金额：
$ 9.54万
依托单位：
Nara Women's University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

In this work, we have, firstly, confirmed the validity the validity of our theory on the coupling of mutual diffusion to viscoelasticity in moderately concentrated polymer solutions, thereby affording a means to determine the diffusion coefficient D, friction coefficient ζ, rubbery plateau modulus L_0, and terminal relaxation time γ_m from the autocorrelation function g^ <(2)>(t) obtained from dynamic light scattering by using the discrete spectrum analysis of g^<(2)> (t) combined with the cumulant analysis. The method has been successively applied to the solutions of some synthetic polymers and also of "living" polymers, i.e., polymer-like micelles. The main results thus obtained are summarized as follows:1) For all the polymer solutions examined, ζ increases with increasing concentration c following the same power-law dependence irrespective of the polymer species, molecular weight M_ω, and solvent quality, indicating that the solvent dependence of D as a function of c is ascribed to that of the osmotic compressibility.2) The L_0 vales sre proportional to c^2 and smoothly connected to the literature values of respective polymers at the bulk state. The results imply that the concept based on the rubber elesticity theory holds not only for polymer concentrates but for rather dilute polymer solutions.3) γ_m is proportional to M^<3.4>_ω irrespective of the polymer-solvent system in good accordance with the 3.4th power-law for the steady-state viscosity.4) Lecithin forms spherical micelles in cyclohexane and the micelles change their shape to the cylindrical with including water. The length of the cylinder is lengthened as the water content is increased, by keeping the distance between lecithin molecules constant.5) The surfactant C_<12>E_6 forms prolate ellipsoidal micelles in aqueous solutions. The micellar solutions exhibit viscoelastic behavior due to network formation by stringlike micelles at large c.

在这项工作中，我们首先证实了我们关于中等浓度聚合物溶液中相互扩散与粘弹性耦合理论的有效性，从而提供了一种从获得的自相关函数 g^ <(2)>(t) 确定扩散系数 D、摩擦系数 ze、橡胶平台模量 L_0 和终端弛豫时间 γ_m 的方法通过使用 g^ (2)> (t) 的离散光谱分析与累积量分析相结合，从动态光散射中获得。该方法已连续应用于一些合成聚合物以及“活性”聚合物（即聚合物状胶束）的溶液。由此获得的主要结果总结如下：1）对于所有检查的聚合物溶液，无论聚合物种类、分子量M_ω和溶剂质量如何，随着浓度c的增加，z随着相同的幂律依赖性而增加，表明D作为c的函数的溶剂依赖性归因于渗透压缩性。2）L_0值sre与c^2成正比，与本体状态下各聚合物的文献值顺利连接。结果表明，基于橡胶弹性理论的概念不仅适用于聚合物浓缩物，而且适用于相当稀的聚合物溶液。3) 无论聚合物-溶剂体系如何，γ_m 都与 M^<3.4>_ω 成正比，这与稳态粘度的 3.4 次方定律很好地一致。4) 卵磷脂在环己烷中形成球形胶束，并且胶束改变其性质用水将其成型为圆柱形。通过保持卵磷脂分子之间的距离恒定，圆柱体的长度随着水含量的增加而变长。5)表面活性剂C_ 12 E_6在水溶液中形成长椭圆形胶束。由于线状胶束在大c处形成网络，胶束溶液表现出粘弹性行为。