NEW CLEAVAGE PHOTOINITIATORS FOR RADICAL POLYMERIZATION - SYNTHESIS AND PHOTOCHEMICAL STUDY OF DIBROMO DERIVATIVES OF DIBENZOYLMETHANE

Dibromo derivatives of p-substituted dibenzoylmethanes have been prepa red. Elucidation of the fragmentation mechanism on continuous irradiat ion has shown that homolytic fragmentation of the C-Br bond is produce d. The quantum yields for chromophore destruction are high and are ind icative of high rates of radical production. A photocalorimetric and r eal time IR (RTIR) study of radical polymerization of acrylic monomers has shown that these compounds are excellent photoinitiators, the bro mine radical being the initiating species.