Local elastic properties of polystyrene nanocomposites increase significantly due to non-affine deformations

TL;DR

This study reveals that the local elastic properties of polystyrene nanocomposites are significantly enhanced near SiO2 nanoparticles due to non-affine deformations, as shown by molecular dynamics simulations and a random matrix model.

Contribution

It introduces a detailed analysis of local elastic property variations in polystyrene nanocomposites and links them to non-affine deformations at the nanoscale.

Findings

Elastic stiffness increases within 1.4 nm of nanoparticles

Density saturates to bulk value at shorter distances

Non-affine deformations significantly influence local elasticity

Abstract

We investigate the local elastic properties of polystyrene doped with SiO2 nanoparticles by analyzing the local density fluctuations. The density fluctuations were established from coarse-grained molecular dynamics simulations performed with the MARTINI force field. A significant increase in polystyrene stiffness was revealed within a characteristic range of 1.4 nm from the nanoparticle, while polystyrene density saturates to the bulk value at significantly shorter distances. The enhancement of the local elastic properties of the polymer was attributed to the effect of non-affine deformations at the length scale below 1 nm, which was further confirmed through the random matrix model with variable strength of disorder.