Polymer stretching in laminar and random flows: entropic characterization

TL;DR

This paper explores how entropy can be used to characterize the coil-stretch transition of polymers in laminar and random flows, providing a unified framework for understanding polymer deformation in different flow conditions.

Contribution

It extends entropic analysis by studying the differential entropy of polymer extension and its logarithm across various flow types, offering new insights into the coil-stretch transition.

Findings

Entropy peaks at the coil-stretch transition.

Logarithmic entropy better describes the transition in random flows.

Entropy effectively distinguishes different flow regimes.

Abstract

Polymers in nonuniform flows undergo strong deformation, which in the presence of persistent stretching can result in the coil-stretch transition. This phenomenon has been characterized by using the formalism of nonequilibrium statistical mechanics. In particular, the entropy of the polymer extension reaches a maximum at the transition. We extend the entropic characterization of the coil-stretch transition by studying the differential entropy of the polymer fractional extension in a set of laminar and random velocity fields that are benchmarks for the study of polymer stretching in flow. In the case of random velocity fields, a suitable description of the transition is obtained by considering the entropy of the logarithm of the extension instead of the entropy of the extension itself. Entropy emerges as an effective tool for capturing the coil-stretch transition and comparing its features in different flows.