纳米粒子在两亲性嵌段共聚物胶束中调控机理的介观模拟研究

Hybrid micelles consisting of amphiphilic block copolymers and inorganic nanoparticles have attracted many attentions as they can provide not only the improved stability but also various functionalities and microstructures. Despite notable achievements in the experimental and theoretical aspects for hybrid micelles, the underlying mechanism of controlling the nanoparticles remains elusive due to the distinct natures of various components involved in the process of preparation.Through the hybrid particle field method the proposed project will invstigate the effects of the rigidity of block copolymer, the manifold properties of the common solvent and the anisotropy of nanoparticles on the morphologies of hybrid micelles and the distributions of nanoparticles,in an attempt to systematically clarify the mechanism of controlling the nanoparticles in the hybrid micelles from the viewpoint of thermodynamic. The developments of the theoretical models not only extend the application of the hybrid particle field method, but also improve the accuracy of the analysis and prediction of simulations. The research results will reasonably elucidate the reported experimental results and provide scientific guidance for applications.

两亲性嵌段共聚物和无机纳米粒子形成的杂交胶束结构不仅能为纳米粒子提供良好的稳定性，而且具有多样化的功能和结构，因而受到了人们的广泛关注。尽管杂化胶束的理论和实验研究均取得了显著进展，但由于其在制备过程中组分繁多且性质各异，迄今人们对纳米粒子调控机理的认识尚不完全清楚。本项目基于混合粒子场方法，研究嵌段共聚物链段刚性、共溶剂性质和纳米粒子各向异性对杂化胶束形态及纳米粒子分布的影响，拟从热力学角度详细阐述纳米粒子在杂化胶束中的调控机理。项目建立的理论模型拓宽了混合粒子场法的应用范围，提高了模拟分析和预测的准确性。研究成果将对已有的实验结果给出更合理的解释，为实际应用提供科学依据。

本项目通过多种计算机模拟方法系统研究了嵌段共聚物稀溶液及其与纳米粒子复合体系的自组装行为。采用自洽场理论，研究了纳米粒子形状和溶剂分子尺寸对复合自组装胶束形态的影响。对于圆形纳米粒子来说，两嵌段共聚物可在纳米粒子表面形成多层膜结构，而对于矩形纳米粒子来说，两嵌段共聚物可在纳米粒子表面形成复合多腔结构。我们还从动力学角度研究了星型嵌段共聚物在稀溶液中的自组装行为，发现具有侧壁纳米结构囊泡形成的动力过程可分为三个主要阶段。针对纳米粒子浓度与嵌段共聚物复合溶液体系，我们发现纳米粒子浓度对是否能够形成囊泡结构有重要影响，纳米粒子在胶束中的分布可通过与柔性链段相互作用进行有效调控。通过连通自洽场理论和格子玻尔兹曼模拟方法，我们研究了嵌段共聚物的稀溶液体系在复杂剪切边界条件下的自组装行为。模拟结果表明，在剪切条件下体系相形态与实验上的结果一致；空泡流动和振荡剪切场对体系自组装结构的作用方式不同：在空泡流动中，结构被明显拉伸，而在振荡剪切条件下，胶束结构容易发生碰撞融合。通过将两种聚合度差别很大的嵌段共聚物放在溶液中进行共混自组装，制备出孔径为1.5nm的多孔滤膜，通过耗散粒子动力学模拟了膜的形成过程并解释了孔径尺寸减小的原因。