Activity-induced stiffness, entanglement network and dynamic slowdown in unentangled semidilute polymer solutions

J Li and BK Zhang and ZY Wang, SOFT MATTER, 20, 5174-5182 (2024).

DOI: 10.1039/d4sm00341a

Active polymers possess numerous unique properties that are quite different from those observed in the system of small active molecules 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 the dynamics observed can be attributed to increased entanglement due to chain elongation. The introduction of activity modification at the chain ends leads to a rapid slowdown in dynamics: high-temperature particles demonstrate reduced diffusion coefficients and longer Rouse relaxation times.

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