Real time study of hybrid sol-gel photopolymerization by UV light

Abstract

Hybrid organic-inorganic materials obtained via sol-gel processing using an organically modified silicon alkoxide have been investigated by liquid ²⁹Si NMR and Real Time Fourier Transformed Infra-Red spectroscopy. Free-radical polymerization was initiated by irradiating the sample under UV-light. Significant structural modifications during irradiation were evident in both the inorganic and organic domains of the hybrid material. It appeared that the degree of condensation of the silicate network was of crucial importance, although the presence of the silicate backbone did not limit the final conversion ratio of the organic polymer. On the contrary, it was found that photopolymerization occurred more efficiently for systems with the higher degree of silicate condensation. The effects of photoinitiator concentration and the functionality of the polymerizable organic moiety on the reaction kinetics were also studied.