Active motion of tangentially-driven polymers in periodic array of obstacles

TL;DR

This study computationally explores how active, tangentially-driven polymers with different flexibilities behave in a periodic obstacle array, revealing how activity and flexibility influence their conformations and transport mechanisms.

Contribution

It provides new insights into the conformational changes and transport modes of active polymers in confined periodic environments, supported by an analytical theory.

Findings

Flexible polymers become localized and caged at low activity.

Stiff polymers exhibit elongated conformations and enhanced diffusion.

High activity enables polymers to overcome confinement and move freely.

Abstract

We computationally investigate the active transport of tangentially-driven polymers with varying degrees of flexibility and activity in two-dimensional square lattices of obstacles. Tight periodic confinement induces notable conformational changes and distinct modes of transport for flexible and stiff active filaments. It leads to localization and caging of flexible polymers inside the inter-obstacle pores, while promoting more elongated conformations and enhanced diffusion for stiff polymers at low to moderate activity levels. The migration of flexible active polymers occurs via hopping events, where they unfold to move from one cage to another. In contrast, stiff chains travel mainly in straight paths within inter-obstacle channels, while occasionally changing their direction of motion. Both the duration of caging and persistent directed migration within the channels decrease with increasing the activity level. As a consequence, at high active forces polymers overcome confinement effects and transport within inter-obstacle pores as swiftly as those in free space. We explain the center of mass dynamics of semiflexible polymers in terms of active force and obstacle packing fraction by developing an approximate analytical theory.