Electroless nickel plating on polypropylene via hydrophilic modification and supercritical carbon dioxide Pd-complex infusion

A supercritical carbon dioxide (scCO(2))-assisted electroless Ni-P plating technique on a polymer substrate was modified and improved for polyolefin polymers. The technique consists of two steps: the first step is the scCO(2)-assisted impregnation of the polymer substrate with Pd(hfa)(2) and the second step is the electroless plating reaction. The high solubility of CO2 in thermoplastic polymers is advantageous to infuse the catalyst precursor, Pd(hfa)(2), to polypropylene (PP), however, the hydrophobic nature of PP makes the electroless plating reaction difficult. The hydrophobicity hinders the diffusion of the aqueous plating solution in the polymer, consequently resulting in a weak adhesion of the metal layer to the substrate. In this study, a polypropylene (PP)-polyethyleneoxide (PEO) block copolymer was blended with PP to increase the hydrophilicity of the PP. Blending the copolymer with PP increased the diffusion of the plating solution in the PP substrate and the Ni-P metal layer was successfully formed onto PP with an average adhesive strength of 7.9 +/- 0.5 N/cm to the polymeric substrate. (C) 2012 Elsevier B.V. All rights reserved.