Synthesis and characterization of polyelectrolyte hydrogels with controlled swelling behaviour

Copolymerization of sulfopropyl methacrylate potassium salt (K-SPMA) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) has been studied in the range 10-90% K-SPMA in the feedstock. The reactivity ratios have been determined for K-SPMA/AMPS copolymers. The copolymer compositions, utilized for determining the reactivity ratio, have been determined from nitrogen content. Crosslinked poly(AMPS) and K-SPMA/AMPS copolymers were prepared in water in the presence of potassium persulfate as initiator and NN-methylene bisacrylamide (MBA) as tetrafunctional crosslinker. Irradiation of K-SPMA and AMPS with an electron-beam was carried out at 50 wt% aqueous solution with low pH and irradiation dose 40-120 kGy. The swelling behaviour of highly crosslinked K-SPMA/AMPS copolymer polyelectrolyte gels in aqueous medium was studied in the presence of different types of salts. The crosslink density, the average molecular weight between the crosslinks and the dissociation constant (pK(a)) of the crosslinked polymer were determined from stress-strain measurements. (C) 2001 Society of Chemical Industry.