STABILITY STUDIES OF ALKOXYSILANES IN AQUEOUS MEDIA

In order to correlate hydrolysis rates under physiological conditions to differences in toxicity of trimethoxysilane, tetramethoxysilane, and methyltrimethoxysilane, the rates of hydrolysis of these compounds were studied in deionized water, sodium phosphate buffer solution at pH 7.4, and 10% rat serum in sodium phosphate buffer at 37.4°C. A strong surface effect was observed on the hydrolysis rates of tetramethoxysilane in different reactors in the following decreasing order: quartz > soft glass (I) > stainless steel > Teflon® > soft glass (II). By using the soft glass (II) reactor as the reaction vessel for hydrolysis experiments, trimethoxysilane and tetramethoxysilane were found to be very unstable in 0.15 M sodium phosphate buffer (pH 7.4) and 10% rat serum (0.15 M sodium phosphate buffer, (pH 7.4) with similar rates of hydrolysis at > 3.0 min−1 (t 1/2;<0.23 min). Under similar conditions, however the rate of hydrolysis for tetramethoxysilane in deionized water was measured to be considerably slower ...