Segmental Lennard-Jones Interactions for Semi-flexible Polymer Networks

TL;DR

This paper introduces a segmental Lennard-Jones potential for semi-flexible polymer networks, improving the modeling of steric interactions by enabling both attraction and repulsion with analytical, computationally efficient expressions.

Contribution

It extends existing integrated interaction models by deriving new potentials for lower-dimensional geometries and introduces a segmental Lennard-Jones potential for more realistic polymer interactions.

Findings

Derived analytical expressions for lower-dimensional configurations.

Compared new potentials with existing models, showing improved realism.

Demonstrated the applicability of the segmental Lennard-Jones potential in simulations.

Abstract

Simulating soft matter systems such as the cytoskeleton can enable deep understanding of experimentally observed phenomena. One challenge of modeling such systems is realistic description of the steric repulsion between nearby polymers. Previous models of the polymeric excluded volume interaction have the deficit of being non-analytic, being computationally expensive, or allowing polymers to erroneously cross each other. A recent solution to these issues, implemented in the MEDYAN simulation platform, uses analytical expressions obtained from integrating an interaction kernel along the lengths of two polymer segments to describe their repulsion. Here, we extend this model by re-deriving it for lower-dimensional geometrical configurations, deriving similar expressions using a steeper interaction kernel, comparing it to other commonly used potentials, and showing how to parameterize these models. We also generalize this new integrated style of potential by introducing a segmental Lennard-Jones potential, which enables modelling both attractive and repulsive interactions in semi-flexible polymer networks. These results can be further generalized to facilitate the development of effective interaction potentials for other finite elements in simulations of soft-matter systems.