Tangentially Active Polymers in Cylindrical Channels

TL;DR

This paper combines analytical and computational methods to explore how active polymers behave in cylindrical channels, revealing how confinement and activity influence their structure and dynamics, and proposing a model for their diffusion.

Contribution

It provides new insights into the effects of activity and confinement on polymer conformation and diffusion, including a broken universal relation and an analytical model for diffusion coefficients.

Findings

Polymer size scaling varies with confinement and activity.

Universal relation between passive polymer sizes is broken by activity.

Long-time diffusion coefficient can be modeled analytically considering channel effects.

Abstract

We present an analytical and computational study characterizing the structural and dynamical properties of an active filament confined in cylindrical channels. We first outline the effects of the interplay between confinement and polar self-propulsion on the conformation of the chains. We observe that the scaling of the polymer size in the channel, quantified by the end-to-end distance, shows different anomalous behaviours at different confinement and activity conditions. Interestingly, we show that the universal relation, describing the ratio between the end-to-end distance of passive polymer chains in cylindrical channels and in bulk is broken by activity. Finally, we show that the long-time diffusion coefficient under confinement can be rationalised by an analytical model, that takes into account the presence of the channel and the elongated nature of the polymer.