# Effects of spherical confinement and backbone stiffness on flexible polymer jamming

## TL;DR

This study uses molecular simulations to explore how spherical confinement and backbone stiffness influence the jamming behavior of flexible polymers, revealing unique mechanical properties and boundary effects compared to repulsive spheres.

## Contribution

It introduces a detailed simulation analysis of polymer jamming in confined spaces, highlighting the effects of backbone stiffness and curved boundaries on mechanical properties.

## Key findings

- Jamming occurs isostatically similar to repulsive spheres.
- Curved walls and backbone bonds create new vibrational modes.
- Boundary effects reduce the bulk modulus in polymers.

## Abstract

We use molecular simulations to study jamming of a crumpled bead-spring model polymer in a finite container and compare to jamming of repulsive spheres. After proper constraint counting, the onset of rigidity is seen to occur isostatically as in the case of repulsive spheres. Despite this commonality, the presence of the curved container wall and polymer backbone bonds introduce new mechanical properties. Notably, these include additional bands in the vibrational density of states that reflect the material structure as well as oscillations in local contact number and density near the wall but with lower amplitude for polymers. Polymers have fewer boundary contacts, and this low-density surface layer strongly reduces the global bulk modulus. We further show that bulk-modulus dependence on backbone stiffness can be described by a model of stiffnesses in series and discuss potential experimental and biological applications.