How a local active force modifies the structural properties of polymers

TL;DR

This paper investigates how a local active force on a polymer's end monomer induces a transition from a compact globule to an elongated structure, affecting its dynamics and conformations.

Contribution

It introduces a model of a Rouse chain with an active terminal monomer and analyzes how local active forces alter polymer structural and dynamical properties.

Findings

Active force causes globule-to-elongation transition.

Relaxation times of Rouse modes are affected by activity.

Bond correlations show over-stretched bonds along the chain.

Abstract

We study the dynamics of a polymer, described as a variant of a Rouse chain, driven by an active terminal monomer (head). The local active force induces a transition from a globule-like to an elongated state, as revealed by the study of the end-to-end distance, whose variance is analytically predicted under suitable approximations. The change in the relaxation times of the Rouse-modes produced by the local self-propulsion is consistent with the transition from globule to elongated conformations. Moreover also the bond-bond spatial correlation for the chain head results to be affected and a gradient of over-stretched bonds along the chain is observed. We compare our numerical results both with the phenomenological stiff-polymer theory and several analytical predictions in the Rouse-chain approximation.