Copolymerization of styrene and diethyl fumarate with ZnBr₂. IV. Comparison between photoinitiation and electroinitiation

Abstract

SynopsisA comparative analysis of photoinitiation and electroinitiation can help elucidate initiation processes in donor-acceptor chargetransfer copolymerization. The technique has been applied to the zinc bromide-catalyzed copolymerization of styrene and diethyl fumarate in methanol. The photocopolymer product was analyzed by GPC, NMR, and elemental analysis. The results showed that 1 : 1 copolymers were formed initially, but changes occurred in both the kinetics and products after the early stages of the r e action. Significant correlations found between the two initiation methods included the initial kinetic order with respect to the initiating process and the effect on product yield of equivalent increases in total initiation energy. The limiting value of zinc bromide for both initiation methods was found to be the same. The data obtained support the contention that the copolymerization proceeds through a donor-acceptor process and that photoactivation of the preformed complex, inducing electron transfer, is a likely initiation process.