INVERSE-EMULSION COPOLYMERIZATION OF ACRYLAMIDE AND QUATERNARY AMMONIUM CATIONIC MONOMERS WITH BLOCK COPOLYMERIC SURFACTANTS - COPOLYMER COMPOSITION CONTROL USING BATCH AND SEMIBATCH TECHNIQUES

An experimental investigation of the inverse-emulsion copolymerization of acrylamide and quaternary ammonium cationic monomers (dimethylamin oethylacrylate, DMAEA and dimethylaminoethylmethacrylate, DMAEM) has b een carried out using both a block copolymeric surfactant (HB246) whos e hydrophilic moiety is polyethylene oxide and whose hydrophobic moiet y is poly(12 hydroxy stearic acid) and sorbitan monoleate (SMO). Our r esults indicate that the choice of surfactant influences strongly the quality of the copolymers produced. For example, more uniform copolyme rs of acrylamide and DMAEA can be synthesized using the block copolyme ric surfactant (HB246) at faster production rates in comparison with s orbitan monoleate (SMO) when utilizing batch reactors. However, a comp osition drift is observed in the inverse-emulsion copolymerization of acrylamide and DMAEM using HB246. A possible explanation for this beha viour is either a reduced reactivity ratio (r(2)) or propagation const ant (k(22)). However, physical effects such as a possible lower interf acial acrylamide concentration are not to be ruled out. It is also sho wn, for the first time, that copolymers of acrylamide and DMAEM of mor e uniform composition can be produced by implementing simple semi-batc h policies with non time-varying feedrates. It is believed that these cationic copolymers would have a higher flocculation efficiency both i n municipal and in industrial water treatment due to their more unifor m distribution of the positive charge along the polyacrylamide backbon e. Copyright (C) 1996 Elsevier Science Ltd.