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A pH‐sensitive semi‐interpenetrating network hydrogel was synthesised by free radical polymerization using a one‐pot method using chitosan (CS) and alanine (AA) as the raw materials, and then the hydrogel was immersed in a solution of the model drug aspirin (Asa) for loading, and subsequently used for drug sustained‐release testing. The effects of the ratio of CS and AA on the internal structure of hydrogels were investigated, and the mechanism of CS/PAA semi‐interpenetrating network hydrogels upon drug slow release was explored. The results showed that increasing the composite ratio of PAA resulted in a subsequent increase in the drug loading capacity of CS/PAA hydrogels and the cumulative release of drugs. When the concentration of the drug‐loading solution was 200 mg/L, the drug loading and encapsulation efficiency of CS/PAA‐1 were 16.23±0.57 (%) and 72.16±3.84 (%), respectively (p < 0.05). The hydrogels showed significant pH‐responsive release properties and pH cycling reversibility, with 25.69±1.27 (%) and 77.21±2.68 (%) cumulative drug release over 24 h in the release media of pH 1.2 (simulating gastric fluid) and 7.4 (simulating intestinal fluid), respectively (p < 0.05), and the pH‐responsive reversible release of Asa was maintained in alternating cycles in the release media with pH 1.2 and 7.4. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, maleic anhydride (MA) was grafted onto methyl cellulose (MC) and then reacted with acrylic acid to synthesize a high gel strength and fast water absorption resin (AA-co-MC-g-MA) by UV polymerization. The reaction conditions of maleylated methylcellulose (MC-g-MA) were investigated, including the ratio of MC to MA, reaction time and catalyst amount. In addition, the reaction conditions for the synthesis of super absorbent resin were as follows: the amount of MC-g-MA, the degree of substitution of MC-g-MA, polymerization time, and the amount of initiator. Under optimal conditions, the maximum water absorption volume of synthetic resin was 2116 g/g, and the maximum salt absorption rate was 139 g/g. The water absorption resin prepared this time had high water absorption, water retention, excellent pH sensitivity, etc. It was hoped that it will have a good application prospect in the field of industrial production and agriculture in the future. [ABSTRACT FROM AUTHOR]

Highlights: [•] Maleylated cotton stalk cellulose (MCSC) was synthesized and as a crosslinker. [•] MCSC-g-PAA superabsorbent was prepared by UV photopolymerization. [•] The effects of various factors on the water absorbency and monomer conversion were investigated. [•] The structure and properties of the superabsorbent materials were evaluated. [•] The obtained superabsorbent was easily degraded by cellulose. [ABSTRACT FROM AUTHOR]

The treatment of dye wastewater is one of most important environmental problems in the world. In this work, the β-cyclodextrin (β-CD) was simply modified and copolymerized with acrylamide and acrylic acid to prepare a novel composite hydrogel as an efficient adsorbent for selective adsorption of cationic dyes. During the adsorption performance tests, the material exhibited excellent removal efficiency of towards of methylene blue (MB), reaching 94.9% in 30 min, and showed excellent selective adsorption in methylene blue/Congo red (CR), methyl blue/methyl orange (MO), methyl green (MG)/ Congo red, methyl green/methyl orange mixture solutions. Studies on the adsorption kinetics suggested that the adsorption behavior follows Pseudo-second-order kinetics model, while the adsorption isotherm of the hydrogel was more consistent with the Freundlich isotherm. In addition, desorption performance of these hydrogels was also investigated in detail, with the screening of the desorption conditions. Under the economical and eco-friendly conditions, it was found that the efficiency of desorption can reach 88% in 75% ethanol solution of oxalic acid, and the adsorption capacity of hydrogel in the next cycle of adsorption still reached 93.4%. Overall, the hydrogel is a potential adsorbent for the efficient cleaning of wastewater and recycling of dyes. [Display omitted] [ABSTRACT FROM AUTHOR]