Significantly Improved Stereocomplexation Ability in Cyclic Block Copolymers

Stereocomplex crystallization in cyclic polymer blend and cyclic block copolymers was investigated by means of dynamic Monte Carlo simulations. Five polymer systems (linear polymer blend, linear diblock copolymer, cyclic polymer blend, cyclic diblock copolymer and tetrablock copolymer) were established. It was interestingly found that the cyclic polymer blend exhibited the weakest stereocomplexation ability, while the two cyclic block copolymers showed stronger stereocomplexation ability than the linear diblock copolymer. This abnormal improved stereocomplexation ability of the cyclic block copolymers can be attributed to the synergy between the ring chain topology and the block copolymer structure. Compared with the linear block copolymers, the ring chain topology confined segmental motions of cyclic polymer chains to smaller regions, and then the segments belonging to the different blocks in the cyclic block copolymers have more chance to contact with each other. In this way, the cyclic block copolymers had better miscibility between segments belonging to different types of blocks, leading to the stronger stereocomplexation ability.