The synthesis and characterization of acrylamide polymer containing R-(+)-cysteine end groups

Water soluble polyacrylamides which contain R-(+)-cysteine end groups were synthesized by using R-(+)-cysteine–Ce(IV) sulfate and R-(+)-cysteine–KMnO4 redox systems in acid–aqueous medium. The dependence of polymerization yields and the molecular weight of polymers on the mole ratio of acrylamide to R-(+)-cysteine (nCys=nCe(IV)) at different temperatures, the polymerization time, the temperature, and the concentration of sulfuric acid was investigated. The increase in the mole ratio of acrylamide to R-(+)-cysteine resulted in an increase in the molecular weight but a decrease in the yield. The increase of reaction temperature from 30°C to 60°C resulted in an increase in the molecular weights and slight increase in the yield of polymer. Ce(IV) and Mn(IV) ions are reduced to Ce(III) and Mn(II) respectively in polymerization reaction. The existence of Ce(III) ion in polymer was investigated by UV–Vis spectrometry and fluorescence measurements. The amount of Mn(II) which is incorporated in the polymer was determined. The mechanism of this phenomenon is discussed.