Ultrathin polymer films on gold surfaces through activation of Si-H bonds

Several poly(siloxane)s and a poly(silazane) were bound to gold surfaces by activation of Si-H bonds with cis-[PtCl2(PhCH=CH2)(2)]. Under the reaction conditions used here, adsorption of the poly(siloxane) is observed exclusi vely in presence of the platinum compound. The resulting ultrathin layers w ere studied with IR spectroscopy at grazing incidence reflection, X-ray pho toelectron spectroscopy, contact angle measurements, and ellipsometry. The layer thicknesses (2.9-5.2 nm) are in the typical range of polymer monolaye rs adsorbed on gold. The wetting properties of the modified gold substrates correspond to those of the pure polymers, indicating that the gold is cove red to a high extent or completely with polymer. The highest contact angles of water (115 degrees) were observed with Si-H-terminated poly(dimethylsil oxane) and are among the highest reported for an ultrathin layer on gold. W e assume that the activator cleaves Si-H bonds. The polymers might be bound to the surface by Au-Si bonds or via Pt-Si species. (C) 1999 Academic Pres s.