  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.
