基于超分子相互作用调控的结晶/离子液晶型嵌段共聚物的可控自组装

Crystalline micelles have been widely investigated due to their controllable morphologies and highly anisotropic features. Nevertheless, regulation mean of crystalline micelles is limited to the crystalline block, while the effort devoted to the conformation of corona segments has been scarce. In this project, to enrich the regulation means of crystalline micelles, crystalline/ionic liquid crystalline block copolymers with different chain structures and compositions will be synthesized. It is expected that the morphology of crystalline micelles will be regulated by supermolecular interaction, i.e., interaction between added molecules and corona segment. The effect of chain structures and crystallization condition on morphologies will be firstly investigated. Then the effect of different counterions and host-guest interaction on crystalline micelles will be studied to reveal the relationships between the reduced tethering density and morphology of crystalline micelles. Finally, uniform-sized single crystals of crystalline/ionic liquid crystalline block copolymers are promoted to form driven by the cooperation of liquid crystalline order and crystallization. Using the single crystals as the self-assembly units, the condition and mechanism of “secondary self-assembly” driven by crystallization will be explored, thus the tailored morphologies between different crystalline block copolymers can be realized. The study of the present project is expected to have an important contribution to regulation of morphologies of crystalline micelles and construction of block copolymer micelles with complex shape both in theory and practice.

结晶性胶束因具有形态可控性好、各向异性显著的特点而受到广泛关注和研究，但目前对其形貌调控主要通过结晶链段实现，而对壳层链段构象关注较少。因此本项目拟通过合成结晶/离子液晶型嵌段共聚物，利用壳层链段与不同分子间的超分子相互作用来调控结晶性胶束的形貌。首先考察链结构和结晶条件对结晶/离子液晶型嵌段共聚物胶束形态的影响；其次，研究不同性质的反离子、主客体相互作用对胶束形态的影响，阐明归一化接枝密度与胶束形态的关系；最后通过液晶和结晶驱动力的协同作用制备尺寸均一的嵌段共聚物单晶，并以该单晶为自组装基元，研究在结晶驱动下，“二次自组装”的条件与机理，以实现不同嵌段共聚物之间的可控自组装。本项目的实施将对调控结晶性胶束的形貌以及构建复杂组装体的嵌段共聚物胶束具有重要的理论和实际意义。

本项目研究了壳层液晶作用对结晶/液晶嵌段共聚物形成二维片状胶束的作用，反离子诱导的嵌段共聚物自组装，结晶液晶型嵌段共聚物的结晶、液晶、相分离的相互影响以及嵌段共聚物自组装聚集体在药物载体方面的应用等。主要研究成果如下：1）发现了嵌段共聚物壳层液晶作用对结晶型嵌段共聚物自组装的作用机理，壳层液晶作用可有效地促使可溶链段链段平行排列，从而降低了归一化接枝密度，实现了二维片状胶束的制备。2）在结晶/液晶嵌段共聚物自组装研究基础上，我们进一步深入研究了其它壳层相互作用对自组装的影响，如通过引入不同的Hofmeister反离子，引入主客体相互作用，实现了在水溶液中自组装形态的转变，揭示了亲水链段在改变反离子后可调控该链段的亲疏水能力，从而实现了不同嵌段共聚物的自组装形态。3）同时，我们还研究了结晶、液晶、相分离三者的相互关系，研究发现结晶可以增强相分离作用，相分离可以促进液晶有序度提高，同时液晶反过来可以改变结晶链段的晶型；另一方面，我们还发现相分离作用在某种尺度上对结晶链段具有强的记忆效应，首次发现了在融体温度以上的球晶双折射现象。4）最后，我们利用嵌段共聚物的自组装作用制备了不同形态的聚集体用来负载不同药物，初步研究了其负载药物和在环境刺激下释放药物的可控性，验证了制备的胶束可用于药用纳米载体。