Stretching effect on intrachain conformational ordering of polymers: A steered molecular dynamics simulation

Abstract

The stretching effect on the intrachain conformational ordering of PE, i PP and i PB-1 single chains was investigated using all-atom steered molecular dynamics simulations. We observed frequent helical reversals and competition between different chirality in i PP and i PB-1 chains during cooling. Simulation results show that imposing proper stretch can greatly promote the formation of helical structures of i PP and i PB-1 chains. Stretch can also cause the helicity transition between 3/1 and 11/3 helix for i PB-1. Generally, stretching with proper force elevates the helix-forming temperature while too large force can cause the instability and even destruction of helices. The end-to-end distance of chains with different stretching force is suggested the control factor of helix formation. Deviation from the optimum helical size results in weakened promotion of helix formation in some extent, and finally leads to the destruction of helical structures. Our results are helpful for understanding the crystallization of helical polymers and the transition between crystalline modifications. • Stretching properly promotes helix formation while overstretch can destroy it. • The helical reversal pathway between different chirality is pointed out. • The R ee of chains with stretching influences the helix formation greatly. • There is a significant impact of stretching on the stable helicity for iPB-1.