Inverse micro-emulsion polymerization of acrylamide in the presence of a mixture of oleophilic/hydrophilic surfactants

Abstract

The effect of sodium dodecyl sulphate (SDS) on the formation of inverse micro-emulsion toluene/sodium bis(2-ethylhexyl)sulphosuccinate (AOT)/water/acrylamide (AAm)/SDS and on polymerization of acrylamide initiated by oil soluble dibenzoyl peroxide was studied. The presence of SDS shifts the value of the volume fraction of aqueous phase (Φaw) at which a two-phase Winsor II system forms, to higher values. It was shown that an increase of the mass ratio of SDS/water led to a decrease of acrylamide polymerization rate, of polyacrylamide particle size and of polyacrylamide molecular mass distribution. It was also found that in the presence of SDS, a nearly constant value for acrylamide polymerization rate in inverse micro-emulsion in the range of Φaw values between 5% and 50% can be obtained. The polymerization kinetics and polymer particle formation were explained as consequences of the initiation of acrylamide polymerization in two reaction loci—in inverse micelles and in the oil macrophase of the inverse micro-emulsion. © 1998 SCI.