ABSTRACT
The effects of hydrolysis and condensation processes on the molecular structure of γ-glycidoxypropyltrimethoxysilane (γ-GPS) in aqueous solutions were investigated using proton nuclear magnetic resonance spectroscopy (1H NMR) and Si-29 NMR spectroscopy. Hydrolysis was characterized by monitoring the production of methanol and the decrease in concentration of SiOCH3 groups in 1% solutions of deuterium oxide using proton NMR. NMR spectroscopy showed that hydrolysis was complete in a 1% γ-GPS solution in deuterium oxide after 34 minutes. Condensation, on the other hand, took a relatively long time to occur. Si-29 NMR was used to characterize the silane in 10% solutions of γ-GPS in water. The Si-29 NMR showed oligomer growth with respect to time. The oligomer growth was correlated to adhesion in wedge test specimens. IR analysis of the γ-GPS films on aluminum showed that several changes occurred when the films were dried at elevated temperatures, including oxidation of the epoxide group and siloxane network formation. The IR spectra correlated with mechanical test data that showed when the epoxide ring was oxidized, adhesion decreased.
