化学学报 ›› 2014, Vol. 72 ›› Issue (1): 30-34.DOI: 10.6023/A13080892 上一篇    下一篇

研究论文

对称AB两嵌段共聚物在均聚物C中的自组装

夏彬凯, 李卫华, 邱枫   

  1. 复旦大学高分子科学系 聚合物分子工程国家重点实验室 上海 200433
  • 收稿日期:2013-08-27 出版日期:2014-01-14 发布日期:2013-10-30
  • 通讯作者: 李卫华,E-mail:weihuali@fudan.edu.cn;邱枫,E-mail:fengqiu@fudan.edu.cn E-mail:weihuali@fudan.edu.cn;fengqiu@fudan.edu.cn
  • 基金资助:

    项目受国家自然科学基金(No. 21174031)资助.

Self-assembling Behaviors of Symmetric Diblock Copolymers in C Homopolymers

Xia Binkai, Li Weihua, Qiu Feng   

  1. Department of Macromolecular Science, State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433
  • Received:2013-08-27 Online:2014-01-14 Published:2013-10-30
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 21174031).

通过自洽平均场理论计算,对对称AB两嵌段共聚物在均聚物C中形成的胶束进行了研究. 在C对A、B组分没有选择性相互作用的情况下,我们观察到了两嵌段共聚物所形成的胶束形状为各向异性的、由间隔A/B层相区构成的类椭球结构. 我们系统考察了胶束的长短径之比与胶束体积、组分间相互作用、均聚物长度之间的关系. 结果表明,当固定组分间相互作用时,胶束的长短径之比随体积变大而减小;当体积增大至一临界值,胶束层数增加,长短径之比发生突变并增大. 给定胶束的结构和体积,增加两嵌段共聚物的不相容性,胶束长短径之比增加并且最终趋于平缓;当固定相互作用及胶束体积时,均聚物的长度越小,长短径之比越大.

关键词: 嵌段共聚物, 自组装, 自洽场理论, 胶束, 长短径之比

The micelle formation of AB symmetric diblock copolymers in C homopolymers (or solvents) is studied by means of the calculations of the self-consistent field theory. Under the condition that C homopolymer has no preferential interaction for any of the two blocks, anisotropic ellipsoidal micelles, which are composed of segmented layers of A/B domains with a normal direction along the major axis of ellipsoid, are observed. The length ratio, the ratio of the major axis of an ellipsoidal micelle to its minor axis, is used to quantify the extent of anisotropy. We systematically study the formation of a single micelle in our calculations, through focusing on the length ratio as functions of the volume of micelles, the A/B interactions as well as the length of homopolymer, instead of considering a huge system consisting of a number of micelles with variable volumes. Our results are presented through three main conclusions. First, with fixed interactions, the length ratio of micelles decreases as increasing the micellar volume. When the micellar volume is raised to some critical extent, one more layer of A or B domains is added into the micelle, which leads to a sudden jump of the major axis, thereby inducing a corresponding increase of the length ratio. Second, for a given micellar stucture with fixed volume, the length ratio of micelle continuously rises up as adding the incompatibility of the two blocks. While the incompatibility rises up to high enough, the length ratio varies more mildly because the energy arising from the packing frustation has overwhelmed the interfacial energy between block copolymers and homopolymers. Third, for a micelle with fixed interaction and volume, the length ratio increases as reducing the length of homopolymer. In a limit case of small molecule solvent, the length ratio goes up to an extremely large value, thereby forming a worm-like micelle. Our results are of great interest for the understanding of the response of the micelles with segmented layers of A/B domains to enviromental conditions, including temperature (imcompatibility), homopolymer (or solvent), and shearing (volume).

Key words: block copolymer, self-assembly, self-consistent field theory, micelle, the length ratio