Acta Chimica Sinica ›› 2013, Vol. 71 ›› Issue (03): 351-359.DOI: 10.6023/A12121107 Previous Articles     Next Articles

Article

具有侧挂胆固醇液晶元的两亲嵌段功能大分子的合成及自组装研究

胡方振a,b, 陈圣典b, 李慧b, 孙景景b, 盛瑞隆b, 罗挺b, 曹阿民b   

  1. a 华东理工大学 材料科学与工程学院 上海 200237;
    b 中国科学院上海有机化学研究所 高分子材料研究室 上海 200032
  • 收稿日期:2012-12-27 出版日期:2013-03-14 发布日期:2013-01-23
  • 通讯作者: 曹阿民 E-mail:acao@mail.sioc.ac.cn
  • 基金资助:

    项目受国家自然科学基金(Nos.20874114,21174160,21002116)资助.

Preparation of New Amphiphilic Liquid-Crystal Diblock Copolymers Bearing Side-on Cholesteryl Mesogen and Their Self-aggregation

Hu Fangzhena,b, Chen Shengdianb, Li Huib, Sun Jingjingb, Sheng Ruilongb, Luo Tingb, Cao Aminb   

  1. a School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237;
    b Laboratory for Polymer Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032
  • Received:2012-12-27 Online:2013-03-14 Published:2013-01-23
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 20874114, 21174160, 21002116).

Amphiphilic block copolymers bearing rigid hydrophobic liquid crystal mesogen have recently attracted broad interests since they could spontaneously self-assemble into functional objects at the micron and/or nanometer scales, and these soft matters bearing high-order hierarchical structures have potential applications in micro-reactors, advanced catalysts, biosensors, drug delivery, biotechnology and so forth. In this work, we designed and successfully prepared a new series of amphiphilic liquid crystal poly(glyceryl methacrylate)-b-poly(6-cholesteryloxyhexyl methacrylate) (PGMA-b-PMA6Chol) with hydrophobic PMA6Chol block bearing end-on cholesteryl mesogen through sequential controlled reversible addition- fragmentation chain transfer polymerization (RAFT) and successive removal of ketal protection groups. Then, their structures and comonomer composition were examined by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). Liquid crystal phase structures and their transition as well as thermal stability of the prepared LC copolymers were characterized by differential scanning calorimeter (DSC), polarized optical microscope (POM), 2D small angle X-ray scattering (2D-SAXS) and thermogravimetric analytic instrument (TGA). Moreover, self-aggregation of these amphiphilic LC block copolymers in mixed solution was investigated by means of UV spectrometer, and the aggregate sizes and morphologies were examined by scanning electron microscopy (SEM) and dynamic light scattering (DLS), respectively. As a result, it was revealed that the LC to isotropic phase transition temperature (TLC-I) of as-synthesized LC block copolymers increased with an increase in rigid LC block content, and the presence of bishydroxyl groups of hydrophilic PGMA strongly influenced the self-assembly and LC phase of rigid hydrophobic block in bulk state. In mixed solvent, the synthesized amphiphilic LC copolymers were found to preferably self-aggregate into core-shell spherical objects with average sizes spanning a range from 0.7 to 2.0 μm when the hydrophobic LC block content was less than 93%, in contrast, the LC copolymer with 93 wt% LC block tended to form open hollow spherical aggregates, showing interesting thermal responsive particle sizes in aqueous solution.

Key words: controlled polymerization, LC block copolymer, amphiphilic polymer, cholesteryl mesogen, self-assembly