Sol-gel derived composites from poly(silicic acid) and 2-hydroxyethylmethacrylate: thermal, physical and morphological properties

Hybrid materials based on poly(silicic acid) and 2-hydroxyethylmetbacrylate were prepared and characterized. The glass transition temperatures of a homologous series of samples were measured by dynamic mechanical thermal analysis and the location of the transition and shape of the spectra shown to be dependent on the morphology of the inorganic phase which was able to be manipulated by variation of synthetic conditions. A number of other techniques including small angle X-ray scattering, electron microscopy, density and free volume measurements were used to help elucidate inorganic-organic miscibility and structure. It was shown that incorporation of organic polymeric phase to crosslinked inorganic silicate led to the formation of the system that is similar to interpenetrating polymeric networks. A high level of miscibility as determined by small angle X-ray scattering and transmission electron microscopy was demonstrated. This was also demonstrated in DMTA traces as seen by the mobility of the organic phase being determined by the degree of crosslinking of the inorganic component. Nonetheless, there appear to be a slight influence of silicate architecture on molecular packing and miscibility. Highly branched, higher molecular weight silicate materials appear to be slightly less miscible. (C) 2002 Elsevier Science Ltd. All rights reserved.