Monte Carlo simulations of stereocomplex formation in multiblock copolymers

Currently, controlling the formation of stereocomplex crystallites (SCs) in enantiomeric PLA blends is a research hotspot. In the present work, we performed dynamic Monte Carlo simulations to study the formation mechanism of SCs in multiblock copolymers. The effects of block number and crystallization temperature on SC formation were revealed. The relative size of block length and crystal thickness is an important factor. In the multiblock copolymers with block length longer than crystal thickness, both the increases of crystallization temperature and block number lead to the increase of SC content attributed to the relatively high degree of supercooling for SC formation and the improved local miscibility between different blocks, respectively. In the multiblock copolymers with block length equal to crystal thickness, each block can just form one crystalline stem, and then different blocks can be more easily alternately parallel-packed during SC formation. The system thus reaches the upper limit of the ability to form SCs. Therefore, both the further increases in crystallization temperature and block number can no longer cause the enhancement in SC formation.