Dynamics of Polymer Decompression: Expansion, Unfolding and Ejection

TL;DR

This paper studies the nonlinear diffusion dynamics of polymer decompression, focusing on expansion and ejection processes, providing exact solutions for expansion and a useful approximation for ejection, reconciling conflicting data.

Contribution

It introduces a uniform approximation scheme for polymer ejection dynamics, offering new insights and resolving discrepancies in numerical results.

Findings

Exact solution for polymer expansion dynamics.

A uniform approximation effectively describes polymer ejection.

Reconciliation of conflicting numerical data on polymer ejection.

Abstract

The dynamics of polymer decompression, i.e., a process from compressed, compact state to the relaxed swoll en conformation, can be formally described as a {\it nonlinear diffusion}. We discuss here two basic examples: (i) the expansion, or unfolding from a compact state, and (ii) the ejection of pressed polymer through a pore. The problem can be solved exactly for the case (i), but not for the latter. Even in such situations, a scheme called {\it uniform approximation} is shown to be useful to get a physical insight involved. Its application to the case (ii) is able to account for conflicting numerical data in a consistent way.