Deformation of polymer films by bending forces

TL;DR

This study uses molecular dynamics simulations to analyze how nano-scale polymer films deform under bending forces, revealing shear-dominated deformation, strangling effects, and fluctuations, bridging particle and continuum mechanics insights.

Contribution

It provides the first detailed characterization of nano-scale polymer film deformation under bending, including dynamic stages and size-dependent behaviors.

Findings

Deformation is shear-dominated.

Strangling effects observed in steady state.

Fluctuations occur during deformation.

Abstract

We study the deformation of nano--scale polymer films which are subject to external bending forces by means of computer simulation. The polymer is represented by a generalized bead--spring--model, intended to reproduce characteristic features of n--alkanes. The film is loaded by the action of a prismatic blade which is pressed into the polymer bulk from above and a pair of columns which support the film from below. The interaction between blade and support columns and the polymer is modelled by the repulsive part of a Lennard-Jones potential. For different system sizes as well as for different chainlengths, this nano--scale experiment is simulated by molecular dynamics methods. Our results allow us to give a first characterization of deformed states for such films. We resolve the kinetic and the dynamic stage of the deformation process in time and access the length scale between discrete particle and continuum mechanics behaviour. For the chainlengths considered here, we find that the deformation process is dominated by shear. We observe strangling effects for the film and deformation fluctuations in the steady state.