Organic-inorganic networks in foams from high internal phase emulsion polymerizations

Hybrid foams, which combine an inorganic polysilsesquioxane network with an organic polystyrene network, were successfully synthesized using high inte rnal phase emulsions (HIPE). Methacryloxypropyltrimethoxysilane (MPS) was c opolymerized radically with styrene (S) and divinylbenzene (DVB) in the org anic phase of the emulsion. The hydrolytic condensation of the trimethoxysi lyl groups formed an inorganic polysilsesquioxane network, which significan tly increased the high temperature modulus and thermal stability of the foa m. The hybrid foam had an open-cell structure typical of polymer foams base d on HIPE (polyHIPE), with a significantly smaller cell diameter than S/DVB polyHIPEs. In the absence of DVB, there is no crosslinked network to restr ict the mobility of MPS and the polysilsesquioxane network is more fully de veloped. At low MPS contents, the thermal stability of the foams is higher for foams with DVB reflecting their higher crosslinking density. At high MP S contents, the thermal stability is higher for foams without DVB, reflecti ng the more fully developed inorganic network. (C) 2001 Elsevier Science Lt d. All rights reserved.