Disentangling Entanglements in Biopolymer Solutions

TL;DR

This paper challenges traditional reptation theory for semiflexible polymers, showing through simulations that disentanglement occurs via correlated constraint release and rotational diffusion, not curvilinear tube motion.

Contribution

It provides new insights into the dynamics of semiflexible polymers, demonstrating that disentanglement is driven by constraint release and rotational diffusion rather than reptation.

Findings

Reptation is not the dominant mode for semiflexible polymers.

Disentanglement occurs via correlated constraint release.

Rotational diffusion mediates stress relaxation.

Abstract

Reptation theory has been highly successful in explaining the unusual material properties of entangled polymer solutions. It reduces the complex many-body dynamics to a single-polymer description where each polymer is envisaged to be confined to a tube through which it moves in a snake-like fashion. For flexible polymers, reptation theory has been amply confirmed by both experiments and simulations. In contrast, for semiflexible polymers experimental and numerical tests are either limited to the onset of reptation, or were performed for tracer polymers in a fixed, static matrix. Here we report Brownian dynamics simulations of entangled solutions of semiflexible polymers, which show that curvilinear motion along a tube (reptation) is no longer the dominant mode of dynamics. Instead, we find that polymers disentangle due to correlated constraint release which leads to equilibration of internal bending modes before polymers diffuse the full tube length. The physical mechanism underlying terminal stress relaxation is rotational diffusion mediated by disentanglement rather than curvilinear motion along a tube.