液滴模板辅助下聚合物初级微球一步法原位自组装制备有序胶体组装体

Self-assembly of nano and micronsized particles can form larger scaled ordered suprastructure of the particles, which have important applications in different fields. Up to date, primary particles with surface charges or functional groups are prepared ahead of their assembly. Highly ordered 2D or 3D colloidal crystals like that in opal are obtained if their self-assembly is carried out on a planar surface, and these colloidal crystals have broad applications in light diffraction, energy band gap etc. However, colloidomes are usually obtained when the self-assembly is conducted on a surface with a curvature such as liquid droplets, and several steps are usually needed, leading finally to the colloidosomes of different size and with low yields. Different from all the reported processes, a fully novel process is proposed in this proposal, in which this self-assembly leading to colloidosomes will be achieved through one step in-situ self-organization of the primary particles by precipitation polymerization of styrene and a crosslinker monomer in a mixed solvent consisting of water and ethanol or ketone in the presence of droplet template of an organic solvent not miscible with the polymerization medium mixture. The surface morphology and the interior structure of the colloidosomes thus prepared will be tunable. The mechanism of the process will be discussed. This process, in comparison with all those reported, is simpler with higher yield and narrower size distribution for the assembled colloidosomes. This will provide a new route to the preparation of colloidosomes. This resarch is therefore of high significance in views of fundamental science and industrial applications.

纳米及微米粒子通过自组装可实现更大范围的胶体有序组装体，在许多领域已获得重要应用。迄今的报道一般是先制备表面含功能基团或电荷的单分散聚合物初级微球，在平面基体上对其组装可获得三维有序的具有蛋白石结构的胶体晶体，在光衍射、能量带隙等方面有重要应用前景；而在具有一定曲率的非平面上(如球形液滴)的组装，一般需经多个繁琐步骤最后获得胶体组装体，且其结构及大小不一、产率极低。不同于迄今报道的所有方法，本课题拟在水和醇或者酮的混合溶剂中通过苯乙烯与交联剂单体沉淀共聚合，在体系中加入不溶于混合溶剂的另一溶剂形成模板液滴，实现沉淀聚合形成的单分散聚合物初级微球的一步法原位自组装，获得微米尺寸、表面和内部结构可控的胶体组装体，并对组装机理进行探讨。该过程操作简单、收率较高，所得微球组装体尺寸均一、表面及内部结构可控，为聚合物微球自组装提供了一个崭新途径。课题既具重要的学术价值，亦具重要的应用前景。

纳米颗粒及微米颗粒在特定条件下可以发生自组装，由此可实现更大范围的胶体有序组装体，此类组装体已在许多领域获得重要应用。由聚合物纳微米级微球自组装是此类研究的热点之一。本课题立项之前的相关研究一般是先制备表面含功能基团或电荷的单分散聚合物初级微球，在平面基体上对其进行组装可获得三维有序的胶体晶体，在光电领域有重要应用前景；在具有一定曲率的非平面上(如球体表面)的组装，一般需经多个繁琐步骤完成，而且获得的组装产物胶体囊(Colloidosomes)结构及大小不一、产率极低。本课题首先在水和乙醇混合溶剂中通过苯乙烯(St)与交联剂单体三羟甲基丙烷三丙烯酸酯(TMPTA)沉淀共聚合制得了高度单分散P(St-TMPTA)聚合物初级微球。在此基础上分别通过一步法和两步法对该聚合物初级微球进行了自组装以制备目标组装体-胶体囊。.一步法微球自组装是指将反应单体加入到含有甲苯或乙苯的水-乙醇混合溶剂中，经引发剂引发聚合后在体系中形成聚合物初级微球实现原位一步自组装。探讨了PSt微球自组装的控制条件。优化的实验条件为：组装介质中水和乙醇体积比为3/7，第三溶剂乙苯液滴模板加入量为10%，TMPTA用量为单体的30 wt%，聚合反应4 h。两步法微球自组装是指先在纯乙醇或者水-乙醇混合溶剂中制得1 μm左右的PSt初级微球，再将干燥后的该微球加入到乙苯-水-乙醇混合溶剂中进行自组装。该过程所得到的结论与一步法基本一致，明显差别之处在于在给定溶剂体系中可实现组装的初级微球量以及组装时间。在类似条件下，以苯为第三溶剂的模板液滴也可以实现甲基丙烯酸酯交联聚合物微球的自组装。.建立了该组装过程胶体囊的形成机理，首先是单体在连续相形成聚合物单分散微球，微球增长到一定尺寸而不能够继续稳定存在于混合溶剂连续相时会向液滴模板相迁移，从而在液滴模板中进行自组装，由此形成本课题设计的胶体组装体。通过一步和两步组装法，在组装体系中加入石蜡，并用与石蜡有良好相容性的十二烯替代St制备的单分散微球，对胶体囊形成过程的组装机理进行了证实。对组装过程中实验条件对最终胶体组装体的影响作了研究。该组装过程操作简单，石蜡成球率和聚合物微球组装率都大于95%，所得微球组装体尺寸均一、表面及内部结构可控，为聚合物微球自组装提供了一个新途径。课题既具重要的学术价值，亦具重要的应用前景。