Polymeric UV Absorbers of the 2-Hydroxybenzophenone Type. III. Tertiary Amine Catalyzed Polymerization of 2-Hydroxy-4(2,3-epoxypropoxy)benzophenone

The tertiary amine catalyzed polymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone (HEPBP) in melt and o-xylene solution was studied. UV, IR, and NMR spectra of the polymer thus obtained were evaluated and its molecular weight was determined. In order to elucidate the polymerization of HEPBP, the model reaction of 2-hydroxybenzophenone with 4-(2,3-epoxypropoxy)benzophenone at an equimolar ratio as well as the reaction of HEPBP with 2,4-dihydroxybenzophenone at a molar ratio of 2:1 was investigated. A reaction mechanism was suggested for the polymerization of HEPBP on the basis of the results obtained. According to this mechanism, a catalytic center originates during initiation, and that center affords phenoxyl anion by reacting with HEPBP. In the following step phenoxyl anion opens the epoxide ring and an alkoxide anion arises. The basic alkoxide anion is stabilized by a proton transfer of a phenolic group. The successive recurrence of these reactions results in the growth of the polymer chain.