Thioketone-mediated polymerization of butyl acrylate: Controlling free-radical polymerization via a dormant radical species

It is demonstrated by experiment and simulation that the commercially available thioketone 4,4-bis(dimethylamino)thiobenzophenone is capable of controlling AIBN-initiated bulk butyl acrylate polymerization at 80 degrees C. On the basis of molecular weight data and from monomer conversion versus time curves, the associated rate parameters are estimated. The addition rate coefficient, k(ad), for the reaction of a propagating chain with the thioketone is close to 10(6) L.mol(-1).s(-1) -1 and the fragmentation rate coefficient, k(frag), is around 10(-2) s(-1) giving rise to large equilibrium constants in the order of 10(8) L.mol(-1). Furthermore, cross- and self-termination of the dormant radical species are identified to be operational.