嵌段共聚物通过自组装形成纳米级的有序微相分离。将液晶基元引入嵌段共聚物将赋予体系多尺度有序性。引入具有独特的光响应性的偶氮苯基团，可使含偶氮苯液晶嵌段共聚物兼具多尺度有序和光响应性，有望作为新型功能材料得到应用。本论文以含有偶氮苯的液晶嵌段共聚物作为研究对象展开系统工作。主要研究内容如下：制备了系列含有偶氮苯的液晶性甲基丙烯酸酯类单体。通过原子转移自由基聚合，得到了含偶氮苯的大分子引发剂。利用大分子引发剂引发制备了系列窄分子量分布的偶氮腰挂液晶ABA三嵌段共聚物。进一步制备了不同的大分子引发剂，通过原子转移自由基聚合，得到了三类具有不同链结构（ABA、AB、BAB）的偶氮尾挂液晶嵌段共聚物。利用紫外可见光谱、热分析、原子力显微镜、透射电镜、X射线散射和中子散射等手段，对含偶氮苯的腰挂液晶嵌段共聚物的凝聚态进行了系统的研究。确认了该聚合物微相分离的平衡相态、有序－无序转变温度和相图。并利用基材表面诱导作用，实现了液晶嵌段共聚物的长程有序微相分离。利用原位中子散射实验研究了磁场对液晶嵌段共聚物的微相分区取向的影响。通过含偶氮两亲液晶嵌段共聚物在选择性溶剂作用下的微相分离，自组装得到了中空的胶束，并研究了其紫外响应性行为。制备了含偶氮苯的光响应性纤维状液晶弹性体。通过掺杂小分子液晶作为增塑剂，降低了液晶聚合物加工温度，使抽丝过程可以在交联反应未显著发生前完成。得到了具有光致形变能力的纤维。以上研究工作制备了4个系列新型的偶氮液晶嵌段共聚物。对含柔性间隔腰挂液晶嵌段共聚物微相分离行为进行了系统研究。得到了可将光能直接转换为机械能的液晶弹性体纤维。这些结果在纳米技术、仿生人造肌肉、光电材料等领域具有重要的应用前景。

Block copolymers composed of both liquid crystalline (LC) and isotropic blocks are attractive canditates for developing new functional materials, such as smart or responsive materials and electro-optical systems. The block copolymers tend to self-assemble into ordered micro/nanometer scale domains, while special functionalities can be introduced via the liquid crystalline parts into the micro/nanostructures. The azobenzene-containing liquid crystalline block copolymers can further introduce light-responsive function into the hierarchical ordered systems and exhibit big potential in the application of nanotechnology, artificial muscle and photoelectric materials. This dissertation focuses on the azobenzene-containing liquid crystalline block copolymers. The main objectives are to synthesis new azobenzene-containing liquid crystalline block polymers, to explore the relationship between the molecular structures and the physical properties as well as functionalities of this kind of polymers, and to establish new methods for preparing photo-responsive materials. The main achievements are as follows.A series of azobenzene-containing liquid crystalline methacrylate monomers were prepared. By using the ATRP method, azobenzene-containing macroinitiators were obtained and successfully initiated the polymerization of the second monomers. The azobenzene-containing side-on liquid crystalline ABA triblock copolymers with different segments ratios and narrow polydispersity of the molecular weights were obtained. Furthermore, different macroinitiators (PC6CN, PtBA, PEO) were prepared, and three series of azobenzene-containing end-on liquid crystalline block copolymers with different chain architectures (ABA, AB and BAB) were obtained.The condensation states of the azobenzene-containing side-on liquid crystalline block copolymers were studied by using UV-vis spectroscopy, thermal analysis (TA), atom force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and neutron scattering (NS). The equilibrium morphology, order-disorder transtion temperature and phase diagram of this series of block copolymers were determined. Silicon oxide was used as the substrates to alignment the side-on liquid crystalline block copolymers with or without azobenzene groups. Magnetic field was employed to alignment the micro-domain and in-situ neutron scattering experiment was carried out. The morphologies of the azobenzene-containing end-on liquid crystalline ABA triblock copolymers were obtained by AFM.Hollow micelles of the azobenzene-containing amphiphilic LC block copolymers were obtained through the self-assembly of the polymers in a mixed solvent of tetrahydrofuran and water.Photoresponsive wires were fabricated from the azobenzene-containing side-on LC block copolymers. For preparing LC elastomer wire, the LC block copolymer was mixed with a thermal-curable component. In order to avoid crosslinking reaction occurring during the wire-drawing process, low-molecular-weight LC (5CB) was also added into the LC polymer system. By this method, LC elastomer wires with molecular orientation were obtained by drawing the melted mixture and following crosslinking reaction.This research work has produced four series of novel azobenzene-containing LC block copolymers with different mesogens. The study of the microphase separation behavior of the side-on liquid crystalline block copolymers could offer some general understanding for such systems. The functional wires exhibiting the photomechanical effects could be applied for micro-actuators. The materials and understanding developed in the thesis could be expected for applications in nanotechnology, artificial muscles and photoelectric devices.