Water uptake in chemically crosslinked poly(acrylamide-co-crotonic acid) hydrogels

The aim of this study was to investigate that swelling capability of acrylamide (AAm) hydrogels by adding hydrophilic co-monomer such as crotonic acid (CA). Superswelling poly(acrylamide/crotonic) acid, poly(AAm-co-CA) hydrogels were prepared by free radical polymerization in aqueous solution of AAm with CA. For each copolymerization, four different composition of CA and a concentration of multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and N,N″-methylenebisacrylamide (NMBA) were used. Equilibrium swelling, some swelling kinetics parameters such as the initial swelling rate, swelling rate constant, theoretical equilibrium swelling and diffusional parameters such as swelling exponent, swelling constant and diffusion coefficients of hydrogels have been determined by swelling studies. At the end of dynamic swelling tests, relative content of CA on the swelling properties were examined. It has seen that, if CA contents were increased, equilibrium swelling of the hydrogels were higher than. Poly (AAm-co-CA) hydrogels were swollen in the range 1843–2577% in water, while poly(AAm) hydrogels swelled as 1729–1798%. Equilibrium water content of poly(AAm-co-CA) hydrogels were calculated in the range 0.9473–0.9626. Swelling exponents of poly (AAm-co-CA) hydrogels has calculated as 0.58–0.69. Water intake of hydrogels followed a non-Fickian type diffusion.