Polymer Infiltrated Nanoporous Metals to Create Bicontinuous Composite Materials*

Most research on polymer composites has focused on the addition of discrete nanofiller to a polymer matrix to enhance properties. However many applications would benefit from a percolated network of the organic or inorganic phase, such as ion conductivity. This work focuses on the development of bicontinuous materials created by infiltrating polymer into nanoporous gold (NPG) thin films. The optical properties of the NPG, characterized via ellipsometry, are reminiscent to those of gold nanorods exhibiting a plasmon peak, which is controllable through the ligament size. Polymer films of amorphous Poly(Styrene) and Poly(2-Vinyl Pyridine) which have different affinities for the gold scaffold, are infiltrated into the NPG through thermal annealing, which provides further control over the optical response. A range of chain molecular weights are studied to probe the relation between chain radius of gyration and average NPG pore size and its effect on film properties. The polymer chains in the confined pores exhibit a slowdown in segmental dynamics measured through the glass transition temperature. The broad tunability of these hybrids represents a unique template for designing functional network composite structures from flexible electronics to fuel cell membranes.