Unexpected relaxation dynamics of a self-avoiding polymer in cylindrical confinement

TL;DR

This study uses simulations to explore how confinement affects the relaxation dynamics of self-avoiding polymers in cylindrical pores, revealing deviations from previous scaling predictions and emphasizing the importance of finite-size effects.

Contribution

The paper demonstrates that the established scaling law for polymer relaxation time under cylindrical confinement is only valid asymptotically, highlighting the need to consider finite-size effects in simulations and experiments.

Findings

Numerical results differ from the classical scaling law for N up to 2000.

The classical scaling law is only valid in the asymptotic limit N >> D^(5/3).

Finite-size effects significantly influence relaxation dynamics in confined polymers.

Abstract

We report extensive simulations of the relaxation dynamics of a self-avoiding polymer confined inside a cylindrical pore. In particular, we concentrate on examining how confinement influences the scaling behavior of the global relaxation time of the chain, t, with the chain length N and pore diameter D. An earlier scaling analysis based on the de Gennes blob picture led to t ~ N^2D^(1/3). Our numerical effort that combines molecular dynamics and Monte Carlo simulations, however, consistently produces different t-results for N up to 2000. We argue that the previous scaling prediction is only asymptotically valid in the limit N >> D^(5/3) >> 1, which is currently inaccessible to computer simulations and, more interestingly, is also difficult to reach in experiments. Our results are thus relevant for the interpretation of recent experiments with DNA in nano- and micro-channels.