Characterization of films of organofunctional silanes by TOFSIMS and XPS

The structures of thin films formed by the silanes N-[2-(vinylbenzylamino)-ethyl]-3-aminopropyltrimethoxysilane (SAAPS) and γ-aminopropyltriethoxysilane (γ-APS) deposited onto mechanically polished zinc or mild steel from dilute aqueous solutions were determined using time-of-flight (TOF) SIMS and XPS. TOFSIMS gave structural information which was highly complementary to the XPS data. Aspects such as silane condensation and crosslinking, oxidation at elevated temperatures, the formation of metallosiloxane bonds, and incomplete hydrolysis were detected by TOFSIMS by virtue of its high mass resolution and unlimited mass range. The structures of the films were found to be strongly dependent on the nature of the substrate, the deposition conditions, and heat treatment of the films.