Dudowicz Jacek, Freed Karl F, Douglas Jack F
The James Franck Institute and the Department of Chemistry, The University of Chicago , Chicago, Illinois 60637, United States.
Materials Science and Engineering Division, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States.
J Phys Chem B. 2016 Jun 30;120(25):5753-8. doi: 10.1021/acs.jpcb.6b03248. Epub 2016 Jun 21.
The phase boundaries of polymer solutions in mixed solvents can be extremely complex due to the many competing van der Waals and associative interactions that can arise in these ubiquitous and technologically important complex fluids. The present paper focuses specific attention on ternary solutions of polymers (B) dissolved in a mixture of two solvents (A, C) that competitively associate with the polymer. We are particularly concerned with explaining the origin of the peculiar phenomenon of cononsolvency in mixed solvents, where a mixture of two individually good solvents behaves effectively as a poor solvent. Our computations are based on a recently developed generalization of Flory-Huggins theory that incorporates the competitive solvation of a polymer by two associating solvents. On the basis of this framework, we evaluate the limit of polymer phase stability (spinodal curves) and the second osmotic virial coefficient [Formula: see text] as a function of temperature and the composition of the pure solvent mixture that is maintained in osmotic equilibrium with the ternary solution. The calculations provide new insights into the miscibility patterns of ternary A/B/C polymer solutions exhibiting cononsolvency.
由于在这些普遍存在且具有重要技术意义的复杂流体中会出现许多相互竞争的范德华力和缔合相互作用，聚合物溶液在混合溶剂中的相界可能极其复杂。本文特别关注溶解在两种与聚合物竞争性缔合的溶剂（A、C）混合物中的聚合物（B）的三元溶液。我们特别关注解释混合溶剂中协同溶剂化这一特殊现象的起源，即两种单独的良溶剂的混合物实际上表现为不良溶剂。我们的计算基于最近发展的弗洛里 - 哈金斯理论的推广，该理论纳入了两种缔合溶剂对聚合物的竞争性溶剂化作用。在此框架基础上，我们评估聚合物相稳定性极限（旋节线）和第二维里系数[公式：见原文]作为温度以及与三元溶液保持渗透平衡的纯溶剂混合物组成的函数。这些计算为呈现协同溶剂化现象的三元A/B/C聚合物溶液的混溶模式提供了新的见解。
