Coarse-grained molecular-dynamics simulations of capped crosslinked polymer films: equilibrium structure and glass-transition temperature

We present our recent results from constant temperature-pressure (NPT) molecular dynamics (MD) simulations of a bead-spring copolymer model, in which the polymer is confined between two crystalline substrates. Our goal was to study the combined effect of the polymer crosslinking density and the degree of confinement on the glass-transition temperature and the equilibrium structure of the films. In the direction perpendicular to the substrates, the polymer chains are ordered in layers of increasing density towards the substrates, for all crosslinking densities and the degrees of confinement. In the direction parallel to the substrates, the polymer films display an amorphous structure, just like in the bulk. The glass-transition temperature increases with confinement and crosslinking density, with the former having a large effect compared to the later.