Synthesis and Swelling Behavior of Acrylamide-Potassium Methacrylate Superabsorbent Copolymers

Abstract

ABSTRACT A series of acrylamide-potassium methacrylate superabsorbent copolymers were synthesized by simultaneous free radical aqueous polymerization using acrylamide (AAm), potassium methacrylate (KMA), and ammonium persulfate (APS)/ N,N,N′,N′-tetramethylethylenediamine (TMEDA) as initiating system in the presence of a crosslinker. The effects of variables such as concentration of hydrophilic monomer (KMA), crosslinker, initiator and activator, and polymerization temperature on swelling capacity have been investigated in detail. In these polymerizations, two different crosslinking agents, namely 1,4-butanediol diacrylate (BDDA) and ethylene glycol dimethacrylate (EGDMA), were employed to study the effect of crosslinker on swelling properties. The swelling kinetic parameters as well as type of water diffusion into the polymer matrix were evaluated at different temperatures for two series of superabsorbent copolymers. The swelling experiments revealed that EGDMA crosslinked superabsorbents have shown higher swelling capacity for all the compositions of AAm/KMA ratio than BDDA crosslinked analogues. Further, the salt sensitivity and de-swelling capacity of the superabsorbent polymers were studied. The pH effect on the swelling ratio of crosslinked copolymers was also investigated.