The Study On The Self-Assembly Of Confined Diblock Copolymer Melt Using Self-Consistent Field Theory

The studies on polymerization and polymer phase structures are the most important projects in the polymer science. The problem that is always attracting the attention of polymer physicists is the studies of the self-assembly of block copolymer. The confined block copolymer will influence on microphase separation. Because of many the problems of the polymer system with the confined polymer system, the studies of confined polymer system has the important theoretical significance and the research background obviously. Due to the great difficulties in experiments and the polymer systems theory, people hope to resolve them through computer simulation, which can overcome the disadvantages of theory and experiments, and provide more valuable data for researchers.In this thesis, the self-consistent field theory (SCFT) is applied to study self-assembly characteristics of melt systems of confined AB coil-rod diblock copolymer, and wealso simulate the self-assembly behavior of the melts composed of AB coil-rod diblock copolymers which is not confined. Comparing the phase diagrams, we analyse the commonalities and differences between them. Therefore, we find that the confined condition influence on the self-assembly of diblock copolymer. The polymer chains of these two systems that we studied contain two kind of segments:A-coiled segment and B-rigid segment. Because of the difference of the proportion of the two kind of segments(A and B), there will be an influence on the self-assembly phase behavior of the system. We change the proportion of the rigid segment, then we have compared the self-assembly of the melt systems of confined AB coil-rod diblock copolymers with that of the melt systems which consist of AB coil-rod diblock copolymers respectively.First, we simulate the self-assembly phase behavior of the melts composed of AB coil-rod diblock copolymers which is not confined. We find stable micelle phase structure, hexagonal-packed strip phase structure, gyriod phasestructure and lamella phase structure for this system with increasing the proportion of the rigid segments. We also find two meta-stabke phase structures, one is perforated lamellar structure, the other is zigzag phase structure. We find the gyriod phase structure only in the symmetric AB coil-rod diblock copolymers ( f rod=50%), and the range of the interaction parameter _χN is very small, only in the vicinity of the disorder-order transition.Secondly, we simulate the self-assembly phase behavior of the melts composed of AB coil-rod diblock copolymers which is confined. First, we establish the model of the confined system. AB coil-rod diblock copolymers are restricted between two boundry surfaces in the direction of Z. We use specular reflection boundry condition in the direction of Z which represent the confined system. But we still use periodic boundry condition in the directions of X and Y. There is none polymer on the boundry surfaces. The boundrys are neutral, in other words, there is not interaction between the boundry and the polymer. Then weprepared the corresponding procedures. After many simulation, we also find stable micelle phase structure, hexagonal-packed strip phase structure, gyriod phase structure and lamella phase structure for this system with increasing the proportion of the rigid segments. We also find the meta-stabke phase structure which is perforated lamellar structure, but we can not find zigzag phase structure.Finally, what we want to say is the differences of the two kind of the systems. We find more gyriod phase structure in the symmetric confined AB coil-rod diblock copolymers (f_rod=50%), the range of the interaction parameter _χN is more wide . With increasing the interaction parameter _χN, we can not find lamella phase structure, but we find the middle phase structure which is the typical lamella and cylinder co-exist morphology. The other difference of the two kind of the systems is that the interaction parameter _χN of disorder-order transition of confined system is more bigger than non-confined system when the proportion of the rigid segments is unchanged. In short, we can see thatbecause of confined systerm, the self-assembly phase behavior of systerm is changed.