Characterization of siloxane films on titanium substrate derived front three aminosilanes

The aim of this investigation was to study the siloxane, -Si-O-Si-, film formation on Ti substrate by using mono-, bis- and tris-aminosilanes. The ultimate goal was to obtain a smooth, well-organized and stable siloxane film with suitable surface energy. Such films are expected to perform well in adhering resins to dental metal alloys when the films contain reactive functional groups. Aminosilanes were prepared as 0.5 vol.% solutions in dilute ethanol (50 vol.% ethanol in deionized water), with their natural pH of ∼9. The substrates were silanized in two ways: silane was allowed to react at room temperature or was cured for 1 h at 110°C. The surface characterization was carried out by reflectance-absorbance Fourier transform infrared spectroscopy (RA-FTIR), x-ray photoelectron spectroscopy (XPS), contact angle measurement and atomic force microscopy (AFM). Siloxane film thickness measurements were not made. According to spectral analysis, all silanes indicated covalent bond formation with titanium. ≡Si-O-Ti≡ and ≡Si-O-Si≡ bonds were clearly seen in the spectra, suggesting that chemical retention had taken place. After curing at elevated temperature, the spectral bands seemed to be stronger than those on samples cured at room temperature. Curing of hydrolyzed silanes at elevated temperature seemed to enhance the siloxane layer formation, derived from aminosilanes, on the Ti substrate. This might have an influence on the hydrolytic stability of organosilane-promoted adhesion between Ti and dental resins. Copyright © 2004 John Wiley & Sons, Ltd.