LIGHT-INDUCED POLYMERIZATION OF NEW HIGHLY REACTIVE ACRYLIC-MONOMERS

Acrylic monomers containing an oxetane, dioxolane, oxazolidone or carbonate group in their structural unit have been shown to copolymerize rapidly and extensively with a polyurethane-diacrylate, upon UV radiation. For the most reactive resin, 50% conversion was reached within 3 ms of exposure to a medium-pressure mercury lamp. The kinetics of these ultrafast polymerizations was studied quantitatively by infrared spectroscopy. The rate of polymerization, photosensitivity, and amount of residual acrylate in the cured polymer were determined for the various monomers studied, and compared to the values obtained with conventional mono-, di-, and triacrylates. The functional group introduced into the monomer unit was shown to have a drastic effect on both the reactivity and the physical characteristics of the photocrosslinked polymer. Soft and highly flexible low-modulus polymers were produced with the oxetane, dioxolane, and chlorinated monomers, while the carbonate-acrylate compounds lead to hard and glassy materials. (C) John Wiley & Sons, Inc.