Inverse emulsion terpolymerization of acrylamide, sodium acrylate, and acryloyloxyethyl trimethylammonium chloride was investigated. Aqueous monomer solutions were emulsified in diesel oil with a blend of two surfactants (SPAN80 and TWEEN80) using 2,2'-azobis(2-amidinopropen)-dihydrochloride as the initiator. The effects of temperature, initiator concentration, monomer concentration and composition, and emulsifier content on the polymerization conversion and the polymer intrinsic viscosity were examined. Polymer intrinsic viscosity increased with a decreasing concentration of initiator and an increasing concentration of monomer. The sizes of the latex particles of the terpolymer emulsions were observed with a scanning electron microscope, and the structure of the terpolymer was identified by FTIR spectroscopy. (c) 2006 Wiley Periodicals, Inc.