Pulling an adsorbed polymer chain off a solid surface

TL;DR

This paper studies how a self-avoiding polymer detaches from a surface under external force, analyzing the process through analytical calculations and simulations to understand the phase transition behavior.

Contribution

It introduces a fixed height ensemble approach to analyze polymer detachment, providing new insights into the phase diagram and fluctuation behavior near desorption transition.

Findings

Phase diagram in h-ε plane derived analytically and via simulations.

Fluctuations and distributions behave differently near transition depending on control parameter.

Desorption transition exhibits distinct properties in fixed height ensemble.

Abstract

The thermally assisted detachment of a self-avoiding polymer chain from an adhesive surface by an external force applied to one of the chain ends is investigated. We perform our study in the "fixed height" statistical ensemble where one measures the fluctuating force, exerted by the chain on the last monomer when a chain end is kept fixed at height $h$ over the solid plane at different adsorption strength $\epsilon$. The phase diagram in the $h - \epsilon$ plane is calculated both analytically and by Monte Carlo simulations. We demonstrate that in the vicinity of the polymer desorption transition a number of properties like fluctuations and probability distribution of various quantities behave differently, if $h$ rather than $f$ is used as an independent control parameter.