Preparation, properties, self crosslinking mechanism, and characterization of UV initiated polyacrylic acid superabsorbent resins

Abstract The self crosslinking polyacrylic acid (PAAsc) superabsorbent resins were prepared by UV irradiation without crosslinking agents and initiators. The effects of reaction factors on water absorbency and gel content of resins were investigated. The mechanism of self crosslinking polymerization was studied by means of 1 H NMR and ESR, while the structure and morphology of the resins were characterized by IR, NMR, and SEM. The results show that the polymerization mechanism and structure of PAAsc superabsorbent resins polymerized through light radiation is significantly different from those polymerized by initiators. The main chain of PAAsc contains double bonds and polar functional groups such as ether groups and ester groups, which improves the hydrophilicity of the main chain and significantly improves the liquid absorption ability of the superabsorbent material. Moreover, the swelling kinetics, salt‐resistance, pH sensitivity, and water retention capacity of the PAAsc superabsorbents were studied. Owing to the remarkable water absorbency, salt resistance property and water retention capacity, this superabsorbent material has a broad application prospect in agriculture.