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采用耗散粒子动力学方法(dissipative particle dynamics,DPD)研究了coil-rod-coil(CRC)三嵌段刚柔共聚物在选择性溶剂中的自组装.在链选择性溶剂中,刚性棒长Lr与柔性链长Lc都影响着CRC溶液的自组装及相转变.随Lr的增大,棒与溶剂的接触面变大界面能升高,为减小体系的自由能,棒嵌段趋向聚集以减少接触面与界面能.随Lc的增大,链的自由伸展构象熵增大,影响着棒嵌段聚集体结构的形成,使棒嵌段的分布更加分散.在研究溶剂性质aCS与棒长Lr对体系自组装影响的情况中,观察到两类有趣的相结构:球形相和胶束相.随着参数aCS从亲链变为中性再到亲棒,在球形相内部,不仅棒相区由球体内部移向球表面,而且棒相区与链相区的层次分布也发生了明显地变化.同样,Lr的改变也影响着球形相内部相区的分布,同时诱导了不同球形相间的构型转变.胶束相包括分段胶束和螺旋胶束两种,形成于棒长较长的情况,胶束相中棒嵌段的排列呈现出明显的液晶相结构.
The self-assembly of coil-rod-coil (CRC) triblock copolymers in selective solvents was investigated by dissipative particle dynamics (DPD). In a chain-selective solvent, Lr and flexible chain length Lc both affect the self-assembly and phase transition of CRC solution.With the increase of Lr, the interface between rod and solvent increases and the interfacial energy increases. In order to reduce the free energy of the system, the rod blocks tend to aggregate To reduce the contact surface and interfacial energy.With the increase of Lc, the free conformation entropy of the chain increases, which will affect the formation of rod-block aggregates and make the distribution of rod-blocks more dispersed.In the study of the properties of aCS In the case of a long Lr affecting the self-assembly of the system, two interesting classes of phases are observed: the spherical phase and the micellar phase. As the parameter aCS changes from a parent to a neutral to a parent, The phase region moves from the interior of the sphere to the surface of the sphere, and the layer distribution of the rod phase region and the chain phase region also changes obviously. Similarly, the change of Lr also affects the distribution of the interior phase region of the spherical phase, The micellar phase includes both segmented micelles and spiral micelles, forming Rod length is long, alignment rod micellar phase block showing a clear liquid crystal phase structure.