2,4-DIMETHYL-3-PENTANONE-SENSITIZED PHOTOPOLYMERIZATION OF VINYL MONOMERS.

In an earlier study it was shown that the efficiency of methyl methacrylate polymerization sensitized by aliphatic ketones depends on the ketone triplet lifetime. These results were interpreted in terms of a competition between photoreactions of the excited states which led to species that could initiate polymerization and triplet quenching by methyl methacrylate. In the reported experiments, the initiation quantum yield in the bulk photopolymerization of vinyl monomers sensitized by 2,4-dimethyl-3-pentanone has been measured for several monomers. The results obtained were interpreted in terms of a mechanism that considers singlet and triplet photocleavage of the ketone, competing with the quenching by the monomer. The quenching process does not lead to free radicals that can initiate the polymerization.