Plectoneme creation reduces the rotational friction of a polymer

TL;DR

This study investigates how plectoneme formation in semiflexible polymers at high rotation speeds reduces rotational friction, revealing a non-equilibrium transition between different dissipation modes.

Contribution

It introduces a scaling and simulation analysis of the transition in torsional dynamics and the role of plectonemes in friction reduction.

Findings

Plectoneme creation occurs above a critical rotation frequency.

Rotational friction is significantly reduced in the non-linear regime.

A non-equilibrium transition separates the linear and non-linear dissipation modes.

Abstract

The torsional dynamics of a semiflexible polymer with a contour length $L$ larger than its persistence length L_p that is rotated at fixed frequency omega_0 at one end is studied by scaling arguments and hydrodynamic simulations. We find a non-equilibrium transition at a critical frequency omega_*: In the linear regime, omega_0 < omega_*, axial spinning is the dominant dissipation mode. In the non-linear regime, omega_0 > omega_*, the twist-dissipation mode involves the continuous creation of plectonemes close to the driven end and the rotational friction is substantially reduced.