Abstract:

We studied the kinetics of the vesicle formation of ABA and AB amphiphilic block copolymers, which have the same chain length and composition but different block sequence, in selective solvent. The simulation results show that the kinetic of the formation of AB diblock copolymer vesicle is different from that of ABA triblock copolymer vesicle. At slow annealing rate, ABA triblock copolymer vesicles are formed via hydrophilic molecules diffusion into the center of spherical micelles, whereas AB diblock copolymer vesicles are formed via oblate membrane closing. The annealing rate does not affect the pathway of spontaneous vesicle formation of AB diblock copolymers. Vesicles of AB diblock copolymers in selective solvent are more likely to be formed by membrane closing. Annealing rates only affect microphase separation process between hydrophobic and hydrophilic blocks. At quick annealing rate, the phase segregation between hydrophobic and hydrophilic blocks is relatively quick and occurs before the formation of vesicle. However, the phase segregation is relatively slow at slow annealing rate and occurs after the formation of vesicle.

Key words: Monte Carlo simulation, Block sequence, Vesicle, Amphiphilic block copolymer