Polymer Infiltrated Nanoporous Metals: A New Class of Composite Material*

Most research on polymer composites has focused on adding discrete inorganic nano-fillers to a polymer matrix in order to impart properties not found in polymers alone. However, properties from ion conductivity to mechanical reinforcement would be greatly improved if the composite exhibited an interconnected network of inorganic and polymer phases. Here, we fabricate bicontinuous composite materials by infiltrating polymer into nanoporous gold (NPG) films. Polystyrene (PS) and poly(2-vinylpyridine) (P2VP) films are infiltrated into the 40nm pores via capillary forces by thermal annealing above the polymer glass transition. The two polymer chains, which have different affinities for the gold scaffold, exhibit slower segmental dynamics with varying strengths inside the confined pores as measured through Tg. The more attractive P2VP shows a 20°C increase in Tg relative to that PS, which shows only a of 6°C increase at a comparable molecular weight. The infiltrated polymer, in turn, stabilizes the gold nanopores against collapse from temporal aging. The broad tunability of these polymer/metal hybrids represents a unique template for designing functional network composite structures from flexible electronics to fuel cell membranes.