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 1H 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.

A multifunctional sodium alginate/polyacrylamide/titanium dioxide (SA/PAM/TiO2) double network composite hydrogel was successfully prepared by sunlight‐induced polymerization and ionic cross‐linking method and the relationship between its structure and properties was studied. During the polymerization process, TiO2 is used as an initiator to promote the polymerization and is homogeneously immobilized on the three‐dimensional double network hydrogel matrix as the active component of photo‐catalysis. The dual network structure and highly hydrophilic functional groups in the structure improves the adsorption capacities of the hydrogel and photocatalytic performance of the catalyst by avoiding the aggregation of TiO2. The influences of different factors, such as the amount of cross‐linker, monomer ratio, titanium dioxide content, and exposure time, on the swelling properties of the hydrogel during the reaction process were investigated. The effects of titanium dioxide content, pH value, and initial concentration of methyl orange solution on the adsorption properties and photocatalytic performance of the hydrogel were also examined. In addition, the environmental applications of the material as a reusable adsorbent and an effective photo‐catalyst for the treatment of dyes were explored. The hydrogel possesses excellent mechanical properties and stability and was recycled for 10 times without any significant decrease in photocatalytic efficiency.

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