Ultraviolet-induced decomposition of acrylic acid-based superabsorbent hydrogels crosslinked with N,N-methylenebisacrylamide

Most acrylic acid-based superabsorbent hydrogels, which have been widely used in many applications, are crosslinked with water-solvable crosslinker N,N-methylenebisacrylamide (NMBA), which is easy to hydrolyze when radiated by ultraviolet, leading to decomposition of the superabsorbent hydrogels. In this article, ultraviolet-induced decomposition of acrylic acid-based superabsorbent hydrogels crosslinked with NMBA was investigated by weight loss method under ultraviolet radiation. The results showed that the decomposition rate of the superabsorbent hydrogels was controlled by ultraviolet-induced activation of amide groups on the networks when the intensity of ultraviolet radiation was low, whereas it was controlled by hydrolysis of amide groups on NMBA molecules when the intensity of ultraviolet radiation was high. The ultraviolet stability of acrylic acid-based superabsorbent hydrogels crosslinked with NMBA can be improved by increasing the neutralization degree of acrylic acid, increasing the dosage of crosslinker NMBA, or introducing acrylamide as comonomer. (c) 2008 Wiley Periodicals, Inc.