Functional Polymers. 4. Polymers of 2,4-Dihydroxy-4'-vinylbenzophenone, New Polymeric Ultraviolet Absorbers

The synthesis of 2,4-dihydroxy-4'-vinylbenzophenone was accomplished in five steps, with an overall yield of 15%, starting with p-ethylbenzoic acid. Pure 2,4-dihydroxy-4'-vinylbenzophenone was polymerized with azobis(isobutyr0)nitrile as initiator; radical copolymerizations with methacrylic acid and styrene were also accomplished. In polymerizations with azobis(isobutyro)nitrile, no interference of the phenol groups of 2,4-dihydroxy-4'-vinylbenzophenone was observed. In copolymerization with styrene using benzoyl peroxide as initiator, the molecular weight of a copolymer containing 3 mol % 2,4-dihydroxy-4'-vinylbenzophenone was found to be significantly higher than that of styrene homopolymer prepared under identical conditions. This effect was also observed in the polymerization of styrene in the presence of a model compound, 2,4-dihydroxy-4'-ethylbenzophenone.