Effect of Interfacial Energy on Capillary Infiltration of Entangled Polymers into Nanoporous Gold

Polymer composites have been widely researched because of their outstanding properties. Typically, polymer nanocomposites (PNC) are fabricated by imparting inorganic nanofillers to a polymer matrix. In this work, we compare the kinetics of polystyrene (PS) and poly(2-vinylpyridine) (P2VP), which are weakly and moderately attracted to the gold surface respectively, into a nanoporous gold scaffold. The infiltration of P2VP is slower than that of the PS. We attribute the slower infiltration kinetics P2VP to the interfacial entanglements between the adsorbed layer (i.e. dead zone) and the adjacent P2VP chains. PS infiltration kinetics inside exhibits a scaling such that t_PS ~ M^1.3, exhibiting a weaker molecular weight dependence compared to bulk behavior(t_bulk ~ M^3.4). P2VP, similarly, exhibits a reduced dependence of infiltration time on molecular weight as t_P2VP ~ M^1.4. For a neutral interaction between polymer and the wall, molecular dynamics (MD) simulation results predicts t ~ M^1.4. We attribute the t_P2VP ~ M^1.4 to the formation of a P2VP deadzone prior to bulk infiltration, thus creating a neutral interaction environment. These results are important for creating a variety of PNCs with loadings that are difficult to achieve by the addition of discrete nanoparticles.