Point force manipulation and activated dynamics of polymers adsorbed on structured substrates

TL;DR

This paper develops a theoretical framework for understanding the activated motion of adsorbed polymers driven by a localized point force on structured substrates, accounting for flexible and semiflexible polymers with complex surface potentials.

Contribution

It introduces a model describing kink-like excitations and their dynamics, including energy calculations and the nucleation process, for polymers under localized forces on structured surfaces.

Findings

Kink shapes, energies, and critical forces are calculated.

Polymer motion involves nucleation and diffusive separation of kink-antikink pairs.

Kink dynamics can be mapped to a simple exclusion process.

Abstract

We study the activated motion of adsorbed polymers which are driven over a structured substrate by a localized point force.Our theory applies to experiments with single polymers using, for example, tips of scanning force microscopes to drag the polymer.We consider both flexible and semiflexible polymers,and the lateral surface structure is represented by double-well or periodic potentials. The dynamics is governed by kink-like excitations for which we calculate shapes, energies, and critical point forces. Thermally activated motion proceeds by the nucleation of a kink-antikink pair at the point where the force is applied and subsequent diffusive separation of kink and antikink. In the stationary state of the driven polymer, the collective kink dynamics can be described by an one-dimensional symmetric simple exclusion process.