Synthesis and swelling properties of HPMC-based superabsorbent hydrogels for water-retention applications

Abstract

In this study, highly swellable hydrogels were synthesized based on hydroxypropyl methylcellulose (HPMC) in the presence of acrylamide (AM), polyacrylamide (PAM), vinyl acetate (VA), urea, bentonite, and sodium bicarbonate. The key factors influencing their structural and functional properties were systematically analyzed. In particular, it was established that variations in monomer composition and concentration, reaction time, and the amounts of chromium(III) nitrate crosslinker and ammonium persulfate initiator significantly affect the swelling kinetics and maximum water absorption capacity of the hydrogels. According to the results, the HPMC/AA/AM/Cr 3+ composition exhibited the highest swelling capacity and was superior to the HPMC/AA/Cr 3+ system. The effect of the ionic environment was also investigated, revealing that increasing the salt valence and concentration in the solution leads to a sharp decrease in the swelling capacity of the hydrogels.