Radical polymerization of methyl methacrylate initiated by an enolizable ketone–carbon black system

Abstract

AbstractThe polymerization of methyl methacrylate (MMA) initiated by an enolizable ketone (R1COCH2COR2)‐carbon black system was investigated. Although enolizable ketone itself could not do so, the polymerization of MMA was initiated by enolizable ketone in the presence of carbon black. In addition, a chloranil‐enolizable ketone system was able to initiate the polymerization of MMA. It was found that the enol form of the ketone and quinonic oxygen groups on the carbon black surface played an important role in the initiation system; namely, it was considered that the polymerization was begun by the ketone radical (R1COCHCOR2) formed by a one‐electron transfer reaction from enolate ion to quinonic oxygen groups. The effect of solvent on the process was also studied. The rate of the polymerization increased, depending on the solvent used, in the following order: benzene < 1,4‐dioxane < dimethyl sulfoxide < N,N‐dimethylformamide < N‐methyl‐2‐pyrrolidone. Furthermore, it became apparent that during the polymerization poly(methyl methacrylate) was grafted onto the carbon black surface (grafting ratio was ca. 40% when benzene was used as solvent) and the carbon black obtained gave a stable colloidal dispersion in organic solvent.