Preparation and properties of acrylic acid grafted onto chitosan derivative-based superabsorbent polymers

Superabsorbent polymers (SAPs) with improved absorbency under mechanical load (AUL) and enhanced antimicrobial properties in hygiene applications are still challenging. In this study, chitosan was modified to prepare quaternized carboxymethyl chitosan (QCMC) to improve water solubility and antimicrobial properties and then used it as backbone to obtain a novel type of superabsorbent polymers (P(AA-AMPS/QCMC)) by introducing acrylic acid (AA) and 2-acryloylamino-2-methylpropanesulfonic acid (AMPS) monomers through grafted copolymerization. FT-IR, XRD, SEM, and TG were used to analyze and characterize the structure of samples. Different factors influencing the absorption capacity, such as neutralization degree, monomer concentration, and crosslinker content, were optimized. Conventional SAPs exhibited low AUL and slow absorption rates due to gel blockage. To overcome these limitations, surface crosslinking was applied to improve both AUL and absorption rates. The SAPs showed absorption capacities of 634 g/g in deionized water and 78.8 g/g in 0.9 wt.% NaCl solution, and reached swelling equilibrium within 30 min. With only a 3% QCMC dosage, the inhibition rates against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were 88.9% and 87.7%, respectively. Exploratory biodegradability tests indicated that these polymers possess degradable properties. This study demonstrates the potential applications of these polymers in hygiene.