Effects of acids on vinyl polymerization initiated by chromous acetate-alkyl halide

Effects of various acids, i.e., acetic, chloroacetic, hydrochloric, and sulfuric acids on the polymerization of styrene initiated by Cr2+–CHCl3 in DMF was studied. These acids reduced the rates of polymerization by Cr2+–CHCl3 initiator systems. This phenomenon could be explained by a decrease of the reducing power of Cr2+ for alkyl halide. On the other hand, chloroacetic acids could initiate the polymerization of styrene without CHCl3 because these acids have active chlorine in the molecule for Cr2+. It was found that the polymer obtained by this initiator system had an endgroup containing chromium carboxylate, therefore this polymer was green in color and insoluble in benzene.