Simulation Study Of Block Copolymer Self-assembly In A Restricted State

In a physical confinement, architecture dimension and surface field would strongly influence block polymers self-assembly. As a result, the systems exhibit different phase behaviors as to those in the bulk. It has been showed such difference can be used to fabricate novel materials in nano-scale. Furthermore, studies on the confinement-induced self-assembly can promote the understanding of intrinsic character of block polymers segregation. For the difference between adjacent systems in a phase diagram those could not be observed in the bulk, which can be easily distinguished in the confined state. In this dissertation, we systematically studied the diblock copolymer and triblock terpolymer self-assembly under planar, cylindrical and spherical confinement using simulation technologies.1. Monte Carlo simulation study on the symmetric diblock copolymer self-assembly under cylindrical confinement. Under neutral surface field, the symmetric diblock copolymer may be "stacked-disc" or "helix" structures; when the surface strongly attracts one block, the system would employ "barrel-cylinder" structures; at suitable surface field, there can form "catenoid-cylinder" and "stacked-circle" structures etc. In our studies, under weak surface field, the "stacked-disc" and "helix" structures are found degenerate.2. Applying Self-consistent field theory (SCFT) to study cylinder-forming diblock copolymer self-assembly in nano-pores. We firstly studied the cylinder-forming diblock copolymer in weak segregation limit. The self-assembled structures in weak segregation are more complex than those in strong segregation limit. And our simulation results are consistent with the available experiments results.3. Applying SCFT to study the cylinder-forming diblock copolymer in different segregation limit self-assembly in spherical confinement. Here, we discussed three diblock copolymer systems in strong, intermediate and weak segregation limits, respectively. For the system in weak segregation limit, which could form "spherical lamellae" or "perforated spherical lamellae"; for the system in strong segregation limit, which could form "dispersed droplets" under unfavorable conditions; and for the system in intermediate segregation limit, it exhibit the phase behavior between those in weak and strong segregation limits.4. Using Monte Carlo simulated annealing method study cylinder-forming triblock terpolymer system self-assembly under planar confinement. By comparing with the phase behavior of cylinder-forming diblock copolymer, we found the difference between triblock terpolymer system and diblock copolymer system. And the triblock terpolymer system is more powerful than diblock copolymer system in retaining cylindrical structure under constraint condition.5. Monte Carlo study on cylinder-forming triblock terpolymer self-assembly in nano-pores. We systematically studied the self-assembled structures under different surface preferences. When the pore wall is neutral, "Bar" structures alter with "helix" structures; when pore wall attract long block, the "perforated cylinder" could form in a broad range of pore diameter; when pore wall attract shorter block, the common structures transition sequence is found in the inner layer that is from "droplets" to cylinder "," flat-cylinder and then "helix".