Chemical Vapor Deposition of Silver on Plasma-Modified Polyurethane Surfaces

Abstract

The surface chemistry of [(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionato)(trimethylphosphine)silver(I)], [(fod)AgP(CH3)3], a silver precursor for chemical vapor deposition (CVD), has been investigated on plasma-modified polyurethane surfaces by means of reflection−absorption infrared spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS). On the unmodified polyurethane surface, the RAIRS and XPS data show that [(fod)Ag(P(CH3)3)] reacts with polyurethane CO, N−H, and C−O−C groups present at the surface by displacing the Lewis base P(CH3)3; these acid−base reactions yield the formation of surface Ag−O and Ag−N bonds. Air plasma treament of the polyurethane surface leads to the incorporation of CO and C−O−O functional groups, as well as the conversion of C−N(H)− into CN− functional groups by the abstraction of hydrogen. RAIRS data obtained following O2 and air plasma treatment showed that, in addition to grafting of functional groups, polyurethane chains change their conformation in the polyurethane film. The increase of silver concentration resulting from CVD is proportional to the increase of oxygen incorporated on the polymer surface. This study shows that CVD on soft polymers can be performed at room temperature.