Polymer Infiltration Kinetics Inside Nanoporous Gold: Effect of Molecular Weight and Polymer-Gold Interaction Energy

Polymer composites are widely studied because they combine the best properties of the filler, typically inorganic, and matrix polymer. Usually, polymer nanocomposites (PNC) are fabricated by adding inorganic nanofillers to a polymer matrix. However, high loading is difficult due to particle aggregation followed by kinetic arresting of the morphology. In this work, a high-filler (ca. 50 vol%) PNC is created by infiltrating polystyrene (PS) or poly(2-vinylpyridine) (P2VP) into a nanoporous gold scaffold exhibiting a bicontinuous structure with nanoscale pores. Infiltration occurs through capillary forces by heating PS (P2VP) above its glass transition temperature. If infiltration is dictated by reptation, the infiltration time should scale as MW^3.4. However, in our studies, polystyrene infiltration time is faster than expected, scaling as MW^1.7. We have also observed that P2VP, which has an affinity with gold, infiltrates at a slower rate when compared with a similar MW as PS. To investigate the enhanced kinetics observed within nanopores, molecular dynamics is used to simulate capillary rise infiltration into bicontinuous nanoporous. The impact of polymer-surface interactions, pore size, chain length, and degree of entanglement are explored. Aside from the enhanced kinetics, the interconnected structure of these composites could facilitate high ion (electron) conductivity, thus enabling enhanced performance for batteries and flexible electronics.