Decreasing Polymer Flexibility Improves Wetting and Dispersion of Polymer-Grafted Particles in a Chemically Identical Polymer Matrix

Abstract

We present a molecular dynamics simulation study of nanocomposites containing homopolymer-grafted particles in a homopolymer matrix, where the graft and matrix chemistries are identical, to elucidate the effect of polymer flexibility on the wetting of the grafted layer by the matrix and the nanocomposite morphology. Decreasing flexibility of the graft and matrix causes increased wetting of the grafted layer by the matrix. This increased wetting of the grafted layer with decreasing flexibility is more significantly driven by decreasing the graft flexibility than by decreasing the matrix flexibility. This is due to a large increase in mixing entropy of the graft and matrix upon wetting rather than the reduction in conformational entropy loss of matrix upon wetting. Due to this improved wetting with decreasing flexibility of the graft and matrix, we observe increased particle dispersion in the polymer matrix.