Different pathways in mechanical unfolding/folding cycle of a single semiflexible polymer

TL;DR

This study investigates the hysteresis behavior of semiflexible polymers during mechanical folding and unfolding cycles, revealing distinct pathways and the importance of a two-dimensional phase space in understanding their conformational transitions.

Contribution

It introduces a minimal two-variable model to describe hysteresis and pathway differences in semiflexible polymer transitions, highlighting the role of structural dynamics.

Findings

Semiflexible polymers show large hysteresis even at slow operation speeds.

Flexible polymers exhibit minimal hysteresis under slow conditions.

Different pathways are involved in loading and unloading processes, explained by a two-variable model.

Abstract

Kinetics of conformational change of a semiflexible polymer under mechanical external field were investigated with Langevin dynamics simulations. It is found that a semiflexible polymer exhibits large hysteresis in mechanical folding/unfolding cycle even with a slow operation, whereas in a flexible polymer, the hysteresis almost disappears at a sufficiently slow operation. This suggests that the essential features of the structural transition of a semiflexible polymer should be interpreted at least on a two-dimensional phase space. The appearance of such large hysteresis is discussed in relation to different pathways in the loading and unloading processes. By using a minimal two-variable model, the hysteresis loop is described in terms of different pathways on the transition between two stable states.