Activity-Induced Stiffness, Entanglement Network and Dynamic Slowdown in Unentangled Semidilute Polymer Solutions

TL;DR

This paper investigates how activity alters the stiffness, entanglement, and dynamics of unentangled semidilute polymer solutions, revealing increased chain size and reduced diffusion due to activity-induced effects.

Contribution

It introduces a novel understanding of how activity modifies large-scale polymer conformations and dynamics, emphasizing the role of activity-induced stiffness and entanglement.

Findings

Activity increases chain size and effective stiffness.

Activity significantly decreases diffusion by over an order of magnitude.

Enhanced entanglement causes dynamic slowdown.

Abstract

Active polymers possess numerous unique properties that are quite different from those observed in the system of small active molecule due to the intricate interplay between their activity and topological constraints. This study focuses on the conformational changes induced by activity, impacting effective stiffness and crucially influencing entanglement and dynamics. When the two terminals of a linear chain undergo active modification through coupling to a high-temperature thermal bath, there is a substantial increase in chain size, indicating a notable enhancement in effective stiffness. Unlike in passive semiflexible chains where stiffness predominantly affects local bond angles, activity-induced stiffness manifests at the scale of tens of monomers. While activity raises the ambient temperature, it significantly decreases diffusion by over an order of magnitude. The slowdown of dynamics observed can be attributed to increased entanglement due to chain elongation.