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

Organic-inorganic hybrids from 2-hydroxyethylmethacrylate (HEMA) and poly(s ilicic acid)s were prepared and characterized. The molecular architecture o f the inorganic phase was studied with Si-29 NMR spectroscopy, and the effe ct of acid concentration and reaction time on the properties of poly(silici c acid) were elucidated Interactions between phases were studied with NMR s pectroscopy and gel permeation chromatography, and the coexistence and conn ectivity of the two phases were investigated. Contrary to previous assumpti ons, evidence was found that indicated that the organic and inorganic phase s of this class of sol-gel materials were not covalently linked. The curing process was studied by infrared spectroscopy, by which the disappearance o f terminal double bonds of HEMA monomer were monitored. Thermogravimetric a nalysis 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.