Molecular simulations of microscopic mechanism of the effects of chain length on stereocomplex formation in polymer blends

Abstract

By means of dynamic Monte Carlo simulations, the effects of chain length on the formation of stereocomplex crystallites (SCs) in polymer blend systems with different chain lengths have been studied. The decrease in chain length can lead to the increase of final SC contents. Three factors contribute to the enhanced SC formation in short-chain systems, including miscibility between polymers of different types, chain mobility and nucleation mode. The systems with shorter chains exhibit higher miscibility between polymers of different types and stronger chain mobility. In this condition, polymer chains have more chance to meet other chains of a different type in their neighbouring regions, and in the meantime the stronger chain mobility leads to lower diffusion activation energy and smaller nucleation energy barrier for the SC formation. In addition, the nucleation mode of intermolecular packing alignment dominates in the systems with short chains, and thus more chains of different types choose to pack alternatively during crystallization. Due to the effects of these factors, the systems with shorter chains exhibit higher final SC contents.