线形三嵌段共聚物刷在选择性溶剂中自组装行为的模拟退火研究

Polymer brushes possess smart responsive properties to external stimuli, and have various applications in tailoring surface proprieties (such as wettability, friction, adhesion) and designing biomedical materials etc. The conformations of molecule chains and the aggregated morphologies formed by the polymer chains will dramatically influence the performance of the materials. Because the triblock copolymers can adopt two special conformations (bridge and loop), the polymer chains can self-assemble into more complex aggregated morphologies, which are not existed in the homopolymer and diblock copolymer systems. In this project, we will mainly focus on the phase behaviors and morphological transitions of grafted triblock copolymers by using a simulated annealing method, and investigate the morphological dependences of the brushes on randomness of the grafting point, solvent quality, grafting density, block length, the incompatibility of different blocks and the induce of grafting board. By calculating the configuration information of the “bridge” and “loop” chains, we will also study the mechanism of the morphological transitions. The current project will be useful in guiding further experimental and theoretical studies, and provide a much more effective and richer guidance in developing functional materials.

聚合物刷体系不仅具有良好的智能响应特性，而且在浸润、摩擦、吸附等材料表面性质调控以及生物相容性等生物医用材料领域具有十分广泛的应用。高分子链的不同构象和聚集体结构会直接影响材料的性能，而三嵌段共聚物体系在构象上有其特殊的桥型和环型选择,使其自组装结构更加丰富，这一点是均聚物和两嵌段共聚物体系所不具备的。但是关于三嵌段共聚物刷体系特殊构象的研究少有报道。本项目以三嵌段共聚物刷为主要研究对象，采用模拟退火方法，在选择性溶剂中考察接枝点位置涨落、溶剂性质、接枝密度、嵌段长度、不同单体的不相容性、基底诱导等因素对ABA和ABC型三嵌段共聚物刷体系自组装形态的影响，研究不同自组装形态的转变规律。并且通过对体系桥型和环型共聚物链的分布等构象信息的统计，研究不同聚集体形态的产生和转变机制。项目的研究结果将成为相关理论和实验研究的有益补充，为材料加工中对结构和性能的调控提供更加有效、丰富的科学依据。

聚合物体系在几十到几百纳米的尺度上可自组装形成丰富的自组装形态，在医药、交通、航空航天等领域均有极为广泛的应用，也因此成为理论和实验研究的热点。而聚合物刷，即一端被接枝或固定到表面的共聚物链，由于在表面改性等领域所发挥的极为重要的作用，也成为聚合物家族中一颗耀眼的明珠。.相较于均聚物刷而言，由于嵌段共聚物刷的链结构更为复杂，在选择性溶剂中可自组装形成更加丰富、复杂的表面形态。在本项目中，我们采用模拟退火方法对ABA型三嵌段共聚物刷在选择性溶剂中的自组装行为进行了系统的研究。通过构建体系的相图、展示形态的截图、计算单体的密度分布曲线和体系中链的折叠率等方式，对诸如接枝点位置的涨落、接枝密度、嵌段长度、粒子间相互做用能等因素对共聚物刷体系自组装行为的影响进行了研究。