星形两嵌段共聚高分子薄膜微相分离的耗散粒子动力学模拟

Microphase Separation of Star-Diblock Copolymer Films by Dissipative Particle Dynamics Simulation

利用耗散粒子动力学模拟研究两类典型的星形两嵌段共聚高分子薄膜的微相分离行为,观察到一系列有序结构,并获得相应的相图.结果表明:(Ax)4(By)4体系的相图比(AxBy)4体系具有更明显的对称性,且前者比后者更易发生相分离,这与体相中的情况相近,而同等条件下,后者比前者更易形成岛状结构;组成相同的星形共聚高分子体系在体相与薄膜中所形成的介观结构之间存在对应关系,且一维受限能够使得该体系所形成的微相分离结构更为多样化;较小的薄膜厚度与较强的A-B组分间的排斥作用均有利于增强所形成结构的有序性.

Microphase-separating behaviors of two typical star-diblock copolymer films have been investigated using the dissipative particle dynamics（DPD） technique.A series of ordered structures and corresponding phase diagrams have been obtained.Results show that,compared to（AxBy）4,the phase diagram of（Ax）4（By）4 is distinctly symmetric.It is easier to carry out phase-separating for the latter than for the former,similar to their behaviors in bulk.Additionally,it is easier for the island phase to appear in（AxBy）4 films under the same conditions.Some structures formed in bulk and film at the same composition fraction can correspond to each other to a certain extent,and one-dimension confinement can make these systems form more kinds of microphase-separating structures.Besides,both thinner film and stronger A-B repulsion can contribute to enhance the order of relevant structures.