Depinning of semiflexible polymers in (1+1) dimensions

TL;DR

This paper provides a theoretical model for the depinning transition of semiflexible polymers from a substrate in one dimension, highlighting the influence of bending rigidity and pinning site distribution.

Contribution

It introduces a novel scaling-based criterion for depinning that incorporates polymer stiffness, pinning site spacing, and bond energy, extending previous models.

Findings

Bending rigidity promotes unbinding via a lever-arm effect.

A melting criterion for depinning is derived based on polymer and pinning parameters.

Limitations of the model are discussed in the context of real systems.

Abstract

We present a theoretical analysis of a simple model of the depinning of an anchored semiflexible polymer from a fixed planar substrate in (1+1) dimensions. We consider a polymer with a discrete sequence of pinning sites along its contour. Using the scaling properties of the conformational distribution function in the stiff limit and applying the necklace model of phase transitions in quasi-one-dimensional systems, we obtain a melting criterion in terms of the persistence length, the spacing between pinning sites, a microscopic effective length which characterizes a bond, and the bond energy. The limitations of this and other similar approaches are also discussed. In the case of force-induced unbinding, it is shown that the bending rigidity favors the unbinding through a ``lever-arm effect''.