Effect of initiator on the structure of hydrogels of cross-linked polyacrylic acid

The gelation kinetics in the static and dynamic modes was studied for hydrogels of cross-linked polyacrylic acid synthesized using two initiating systems: the widely used system ammonium persulfate-tetramethylethylenediamine and the system ammonium persulfate-sodium sulfite-Mohr’s salt, which has not been used for this synthesis previously. The monomer concentration was varied, with the monomer/cross-linking agent ratio kept constant. The pH dependences of the gel swelling were determined, and the effective degrees of cross-linking were calculated in relation to the monomer concentration. The factors that give rise to defects affecting the regularity of the gel network structure and the degree of gel swelling were analyzed.