All-Wet Metallization of Chemically Modified Polydimethylsiloxane with Self-Assembled Monolayers

Electroless Ni–P films were deposited on polydimethylsiloxane to metallize the polymer substrate. Two types of self-assembled monolayers, γ-aminopropyltriethoxysilane and γ-aminopropyltrihydroxysilane, which was formed by the hydrolysis of γ-aminopropyltriethoxysilane, were used to improve the adhesion of the metal thin films. Prior to coating with the self-assembled monolayers, surface modification of polydimethylsiloxane was carried out by treatment with oxygen plasma. Pd(II) was adsorbed on the surface-modified polydimethylsiloxane with self-assembled monolayers and reduced to Pd(0) by immersion in aqueous sodium hypophosphite solution. After pretreatment of the polydimethylsiloxane, the electroless Ni–P film was deposited. X-ray photoelectron spectroscopy was used to monitor the chemical surface modification of the polydimethylsiloxane substrates subjected to plasma treatment and silanization and to help understand the mechanisms of Pd catalyst chemisorption on the substrate through the use of a typical palladium chloride solution. In addition, stud pull tests were used to measure the adhesion between the films and substrates. Compared to films on bare polydimethylsiloxane, the film adhesion strength was improved by surface modification.