Adsorption of Externally Stretched Two-Dimensional Flexible and Semi-flexible Polymers near an Attractive Wall

TL;DR

This paper analytically investigates how an attractive wall influences the behavior of a stretched two-dimensional flexible or semi-flexible polymer, revealing a first-order transition in monomer-wall contact depending on temperature and force.

Contribution

It introduces a model combining wall attraction, polymer flexibility, and external stretching, and characterizes the phase transition with analytical and simulation methods.

Findings

Wall attraction induces a first-order transition in monomer-wall contact.

Phase diagram maps the transition as a function of temperature and force.

Monte-Carlo simulations confirm the analytical results.

Abstract

We study analytically a model of a two dimensional, partially directed, flexible or semiflexible polymer, attached to an attractive wall which is perpendicular to the preferred direction. In addition, the polymer is stretched by an externally applied force. We find that the wall has a dramatic effect on the polymer. For wall attraction smaller than the non-sequential nearest neighbor attraction, the fraction of monomers at the wall is zero and the model is the same as that of a polymer without a wall. However, for greater than, the fraction of monomers at the wall undergoes a first order transition from unity at low temperature and small force, to zero at higher temperatures and forces. We present phase diagram for this transition. Our results are confirmed by Monte-Carlo simulations.