Chemical structure of composites derived from poly(silicic acid) and 2-hydroxyethylmethacrylate

Organic-inorganic hybrids from 2-hydroxyethylmethacrylate (HEMA) and poly(silicic acid)s were prepared and characterized. The molecular architecture of the inorganic phase was studied with Si-29 NMR spectroscopy, and the effect of acid concentration and reaction time on the properties of poly(silicic acid) were elucidated Interactions between phases were studied with NMR spectroscopy and gel permeation chromatography, and the coexistence and connectivity of the two phases were investigated. Contrary to previous assumptions, evidence was found that indicated that the organic and inorganic phases of this class of sol-gel materials were not covalently linked. The curing process was studied by infrared spectroscopy, by which the disappearance of terminal double bonds of HEMA monomer were monitored. Thermogravimetric analysis profiles showed that the inorganic phase content was about 10 wt %, and it was varied slightly by changes in the molar ratio of the components. (C) 2001 John Wiley & Sons, Inc.