Environmentally benign electroless nickel plating using supercritical carbon-dioxide on hydrophilically modified acrylonitrile–butadiene–styrene

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Electroless Ni-P plating using supercritical carbon dioxide (scCO2) in conjunction with copolymer-based hydrophilic modification was applied to an acrylonitrile–butadiene–styrene (ABS) substrate. The surface of ABS substrate was hydrophilically modified by blending with a multi-block copolymer, poly(ether-ester-amide)s (PEEA), in injection molding process. The substrate was then impregnated with Pd(II)-hexafluoroacetylacetonate, Pd(hfa)2, using scCO2, followed by the electroless plating reaction. ABS/PEEA substrates with different PEEA to ABS blend ratios and different volume ratios of butadiene to the styrene–acrylonitrile copolymer (SAN) matrix were prepared to investigate how the dispersed PEEA and butadiene domains affected the blend morphology and the adhesive strength of the plating metal-to-polymer contact. Increasing the PEEA copolymer to ABS blend ratio increased the mass transfer rate of the plating solution in the ABS substrate. Consequently, the metal–polymer composite layer became thicker, which increased the adhesive strength of the metal-to-polymer contact because of the anchoring effect. The butadiene domains appeared to attract the Pd catalyst precursor, and thus, the proportion of butadiene in the ABS matrix also affected the adhesive strength of the contact between the metal layer and the substrate. The ABS substrate was successfully plated with a Ni-P metal layer with an average adhesive strength of 9.1 ± 0.5 N cm−1 by choosing appropriate ABS/PEEA blend ratios and a Pd(hfa)2 concentration.