COPOLYMERS OF ACRYLAMIDE AND QUATERNARY AMMONIUM CATIONIC MONOMERS - CHARACTERIZATION BY HPLC AND COPOLYMER COMPOSITION CONTROL

Copolymers of acrylamide with quaternary ammonium cationic monomers (d imethylaminoethylacrylate-methyl chloride, DMAEA and dimethylaminoethy lmethacrylate-methyl chloride, DMAEM) have been synthesized by inverse -emulsion copolymerization using both sorbitan monoleate (SMO) and a b lock copolymeric surfactant (HB246) whose hydrophilic moiety is polyet hylene oxide and whose hydrophobic moiety is poly-12 hydroxy stearic a cid. Residual monomer concentrations were determined by means of an op timized HPLC method using a CN coated column. The optimized conditions consist of an acetonitrile-water mobile phase with a ratio of 50: 50 vol% with dibutylamine used as an additive to reduce the adsorption of the cationic monomer at a concentration of 0.01 M and phosphoric acid to adjust the pH. The results indicate that the choice of surfactant influences strongly the quality of the copolymers produced. For exampl e, more uniform copolymers of acrylamide and DMAEA can be synthesized using the block copolymeric surfactant (HB246) at faster production ra tes in comparison with sorbitan monoleate (SMO). However, a compositio n drift is observed in the inverse-emulsion copolymerization of acryla mide and DMAEM using HB246. It is shown that uniform water soluble cop olymers of acrylamide and DMAEM can be produced by implementing semi-b atch policies with non time-varying feed-rates.