Structure of a Thermoset Polymer near an Alumina Substrate as Studied by Dissipative Particle Dynamics

We performed dissipative particle dynamics (DPD) simulations to investigate the structure and cross-link formation dynamics of a thermoset polymer while interacting with a metal-oxide surface. For characterizing the polymer–surface interactions we used the surface excess, quantifying the surface selectivity of different functional groups. Mesoscopic polymer–surface interactions are determined by matching the surface excess, as computed with atomistic molecular dynamics (MD), with those for DPD, thus realizing a coupling between the mesoscopic and atomistic scales. In the structure prior to cross-linking, we observe that some functional groups prefer to be located at the interface while others are repelled. This largely determines the final cross-linked structure near the metal-oxide interface. The initial preference for cross-links to form is in the bulk region. However, at longer times toward the equilibrium structure, the trade-off between the epoxy–alumina interactions causes migration of reacted groups to the surface.