The influence of one block polydispersity on phase separation of diblock copolymers: The molecular mechanism for domain spacing expansion
The influence of one block polydispersity on phase separation of diblock copolymers: The molecular mechanism for domain spacing expansion
复制标题
一嵌段多分散性对二嵌段共聚物相分离的影响：域间距扩展的分子机制
DOI：
10.1016/j.polymer.2013.04.064
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发表时间：
2013-06-01
期刊：
影响因子：
4.6
通讯作者：
Lu, Zhong-Yuan
中科院分区：
文献类型：
--
作者：
Li, Yue;Qian, Hu-Jun;Lu, Zhong-Yuan
采用耗散粒子动力学方法研究了A-嵌段多分散性对AB-嵌段共聚物相行为的影响。Lynd和Hillmyer关于在不同偏析下多分散性诱导的畴间距扩展的实验结果（Macromolecules 2005，38，8803）被很好地再现，并根据界面自由能和畴中心中的分子拉伸来解释。在多分散体系中，短嵌段共聚物作为增容剂优先聚集在A/B界面，导致界面自由能降低。同时，发现畴中心主要被长块占据，长块反过来又决定了相应畴的间距。更重要的是，多分散性的增加将向系统中引入更多的长嵌段，因此将增强域中心的分子堆积和拉伸。这种在畴中心的链拉伸和界面自由能的降低被发现在更强的偏析，这将导致更严重的畴间距扩大与多分散性增加更严重。(C)2013爱思唯尔有限公司保留所有权利。
Comprehensive dissipative particle dynamics simulations are performed to investigate the effect of A-block polydispersity on the phase behavior of AB-diblock copolymers. The experimental results of Lynd and Hillmyer on polydispersity induced domain spacing expansion at different segregations (Macromolecules 2005, 38, 8803) are well reproduced and explained in terms of interfacial free energy and molecular stretching in domain center. Short block copolymers in polydisperse system are found to preferably accumulate at A/B interface as compatibilizers causing a reduction in interfacial free energy. At the same time, domain centers are found mainly occupied by long blocks which in turn determining the spacing of the corresponding domain. More importantly, increase in polydispersity will introduce more long blocks into system and therefore will enhance the molecular packing and stretching in the domain center. Such chain stretching in domain center and reduction in interfacial free energy are found to be more severe at stronger segregation, which will lead to more severe domain spacing expansion with increasing polydispersity. (C) 2013 Elsevier Ltd. All rights reserved.