Fabrication of Small Pore-Size Nickel Foams Using Electroless Plating of Solid-State Foamed Immiscible Polymer Blends

A novel fabrication process of small pore-size nickel foams has been developed using electroless plating of solid-state foamed immiscible polymer blends. Ethylene acrylic acid (EAA) and polystyrene (PS) were melt-blended with extrusion to obtain a dual phase cocontinuous morphology. Gas saturation and foaming studies were performed to determine appropriate process conditions for foaming of the two-phase material. Open-celled polymer templates were obtained by extracting the PS phase with dichloromethane (DCM). The templates were subsequently used for nickel foam plating in ethanol-based electroless plating solutions. Nickel foams with pore sizes on the level of tens of micrometers and porosity above 90% were fabricated. It was found that gas concentration and foaming temperature were major process variables significantly affecting the foam porosity. Foaming allowed faster PS extraction and higher porosity of the nickel plating templates. Because of the small pore size, ethanol-based solutions need to be used to ensure the infiltration of plating solutions. The developed process is a bulk method and can be used for large-scale fabrication of small pore-size nickel foams with high porosity.