P-NITROACETANILIDE IN THE PRESENCE OF TRIETHYLAMINE AS A PHOTOINITIATOR SYSTEM FOR VINYL POLYMERIZATION

The polymerization rate of methyl methacrylate photosensitized by p-ni tro-acetanilide in the presence of triethylamine was measured as a fun ction of the amine and monomer concentrations. The polymerization proc eeds readily in high-polarity media (acetonitrile/monomer)but is negli gible in nonpolar media. The polymerization rate increases with the am ine concentration up to 0.15M. Further increase in amine concentration does not change the polymerization rate. A similar behavior was obser ved for the photobleaching of the nitro compound. ESR studies show the formation of a nitro and an amine free radical, the latter free radic al being the active species that adds to the monomer. (C) 1997 John Wi ley & Sons, Inc.