Force-induced desorption of a linear polymer chain adsorbed on an attractive surface

TL;DR

This paper investigates how an external force causes a polymer chain to detach from an attractive surface, revealing different behaviors in two and three dimensions through exact enumeration analysis.

Contribution

It provides a detailed analysis of the force-temperature phase boundary for polymer desorption, including the discovery of re-entrance behavior in three dimensions.

Findings

In 2D, the critical force increases monotonically as temperature decreases.

In 3D, the critical force exhibits re-entrance, passing through a maximum at intermediate temperatures.

The probability distribution of the vertex height offers insights into the chain's behavior under force.

Abstract

We consider a model of self-avoiding walk on a lattice with on-site repulsion and an attraction for every vertex of the walk visited on the surface to study force-induced desorption of a linear polymer chain adsorbed on an attractive surface and use the exact enumeration technique for analyzing how the critical force for desorption $f_c(T)$ depends on the temperature. The curve $f_c(T)$ gives the boundary separating the adsorbed phase from the desorbed phase. Our results show that in two dimensions where surface is a line the force $f_c(T)$ increases monotonically as temperature is lowered and becomes almost constant at very low temperatures. In case of three-dimensions we, however, find re-entrance, i. e. $f_c(T)$ goes through a maximum as temperature is lowered. The behaviour of the polymer chain at different values of temperature and force is examined by calculating the probability distribution of the height from the surface of the vertex at which external force is applied.