No abstract

synopsis Dimethylaniline (DMA) induces chain transfer in the zinc bromide-complexed donoracceptor polymerizations of styrene-acrylonitrile t o form alternating copolymers. The Mayo plots are linear, but the rates decrease with incresse in DMA and depadative chain transfer occurs. Although conventional free-radical transfer agents have negligible effect on the rates or molecular weights, a twentyfold reduction of molecular weight is obtained with DMA. Spectroscopic data indicate the formation of an equimolar complex of DMA and ZnBrs, but the lowering of molecular weight is not attributable to the reduction of the effective ZnBrz concentration. A possible mechanism involving a competition between [ZnBr2(DMA)2] and [ZnBrz,DMA,AN] is suggested.