Photoinitiation of acrylamide polymerization using the dianions of rhodizonic and croconic acids

Abstract

Polymerization of acrylamide has been initiated by the photochemical reactions of the dianions of croconic acid (1,2-dihydroxycyclopentenetrione) and rhodizonic acid (1,2-dihydroxycyclohexenetetrone) in the presence of various acceptor molecules. Photoinitiation was most efficient with croconic acid where a maximum quantum yield for polymerization of 2 x 103 was observed in neutral solution. Kinetic studies using this initiator showed that the rate of polymerization was a linear function of the concentration of monomer and proportional to the square root of the light absorbed by the croconate dianion. The rate of initiation of radicals calculated from the rate of polymerization was compared with the rate of production of radicals calculated from previous studies of the photochemistry of the croconate dianion and the mechanism of photoinitiation is discussed. © 1992 John Wiley & Sons, Inc.