Micellar interaction and its catalytic role in the polymerization of acrylamide catalyzed by bisulfite

Abstract

A micellar interaction of cetyltrimethylammonium bromide (CTAB) with sodium bisulfite was observed, which coincided with a pH shift. This shift probably resulted from the formation of a complex that seemed highly susceptible to oxidation. Bisulfite-catalyzed polymerization of acrylamide was thus accelerated by the addition of CTAB to the polymerization system. The rate of acceleration of a CTAB-containing system was nearly three times as high as that of a CTAB-free nonmicellar system at pH = 5.3, which is an optimum for the highest rate for all cases of polymerization. It was observed that there were some salt effects in nonmicellar simple systems with a gradual increase in R p in proportion to the salt concentration. The unique kinetic feature of a CTAB-micellar system, was in sharp contrast, was a slow increase in R p at the CMC region but a sharp increase in R p at [CTAB] ⋍ 8.0 × 10 ṫ M. The R p approached a limiting value with further increase of CTAB concentration.