SYNTHESIS OF HYBRID ORGANIC-INORGANIC MATERIALS FROM INTERPENETRATINGPOLYMER NETWORK CHEMISTRY

Organic-inorganic interpenetrating polymer networks were synthesized w ith an SiO2 phase made by sol-gel chemistry and the organic phase made from poly(2-hydroxyethyl acrylate). The resultant morphologies were c haracterized by small-angle scattering and electron microscopy. When t he vinyl polymerization is more rapid than the sol-gel reaction, gross phase separation occurs giving a heterogeneous structure. For compara ble rates of the two polymerizations, the specimens have a dendritic m orphology on the scale of 0.5 mu m. The more rapid formation of the si lica phase relative to the organic network produces rigid and opticall y transparent materials, with a finely divided structure as seen by tr ansmission electron microscopy. The glass content of these materials i s about 0.15 g/g and the sizes of the SiO2-rich domains are 100 Angstr om or less. Addition of tetrakis(2-(acryloxy)ethoxy)silane was also st udied and found to promote phase mixing between the organic and inorga nic phases.