Macromolecules, Vol.52, No.14, 5074-5085, 2019
Proximity to Graphene Dramatically Alters Polymer Dynamics
Proximity to graphene has an extraordinary effect on the dynamics of entangled chains, as evidenced by strong slowing of thermally stimulated fluctuations at the surface of a thin supported film of polystyrene (PS) when a single layer of graphene is placed between the supporting substrate and the PS film. This slowing is due to a layer of highly viscous polymer next to the substrate being thicker for graphene (75 nm or 7.5R(g)) than for silicon (13 nm or 1.3R(g)). Molecular dynamics simulations of unentangled PS chain melts on silicon and on multiple layers of graphene show that the work of adhesion with graphene is roughly 4 times larger than that with silicon. In addition, PS chains adjacent to silicon readily form loops, with phenyl rings pointing predominantly toward the substrate. Chains adjacent to graphene more readily form trains, with the phenyl rings predominantly parallel to the graphene.