Effect of Solvent Molecular Size on the Self-assembly of Amphiphilic Triblock Copolymer in a Selective Solvent with a Monte Carlo Simulation

The effect of solvent molecular size on the self-assembly of ABA amphiphilic triblock copolymer in a selective solvent was studied by means of Monte Carlo simulation. The simulative results show that the solvent molecular size is one of the key factors that determine the morphologies of the copolymer aggregates. The morphologies formed by ABA amphiphilic triblock copolymers changed from spheres to rod and then to vesicle by increasing the solvent molecular size. By analyzing the variations of the contact number between monomers, it was found that the morphological transition was induced by the decreasing of the solvent solubility when increasing the solvent molecular size. Moreover, the phase diagrams in terms of the core-solvent interaction and the solvent molecular size as well as the corona-solvent interaction and the solvent molecular size were given, respectively. The results revealed that increasing solvent molecular size, core-solvent interaction and decreasing corona-solvent interaction had an equivalent effect on the self-assembled structure for the ABA amphiphilic triblock copolymers.