Factors affecting the properties of superabsorbent polymer hydrogels and methods to improve their performance: a review

The ability of superabsorbent polymers (SAPs) to absorb and retain a large amount of aqueous solution enables their applications in agriculture, medicine and water treatment. As a result, there were numerous studies reporting the present status and application prospects of raw materials and the mechanism of cross-linking agents. Conversely, there was a lack of research on the factors affecting SAP performance and the summaries of methods to improve performance. In this paper, a comprehensive and systematic review based on the structure and water absorption mechanism of SAPs was performed. The methods of improving the performance and main factors of the synthesis of SAPs, such as monomer, cross-linking agent, initiator, ion concentration, hydrophilic group, neutralization degree and particle size, were discussed. The improvement methods of salinity tolerance, reusability, water absorption and rate of SAP were explored. In addition, some applications and future research in SAPs are also discussed in this review.