Copolymers of acrylamide and quaternary ammonium cationic monomers: Characterization by HPLC and copolymer composition control

Abstract

AbstractCopolymers of acrylamide with quaternary ammonium cationic monomers (dimethylaminoethylacrylate‐methyl chloride, DMAEA and dimethylaminoethylmethacrylate‐methyl chloride, DMAEM) have been synthesized by inverse‐emulsion copolymerization using both sorbitan monoleate (SMO) and a block copolymeric surfactant (HB246) whose hydrophilic moiety is polyethylene oxide and whose hydrophobic moiety is poly‐12 hydroxy stearic acid. Residual monomer concentrations were determined by means of an optimized 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 example, more uniform copolymers of acrylamide and DMAEA can be synthesized using the block copolymeric surfactant (HB246) at faster production rates in comparison with sorbitan monoleate (SMO). However, a composition drift is observed in the inverse‐emulsion copolymerization of acrylamide and DMAEM using HB246. It is shown that uniform water soluble copolymers of acrylamide and DMAEM can be produced by implementing semi‐batch policies with non time‐varying feed‐rates.