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Superabsorbent polymers (SAPs) are a class of cross-coupled hydrophilic networks that have an extraordinary capacity to absorb and retain water. It is primarily because of the additional ionic cross-linking of SAPs, their porous wavy structure, a large number of hydrophilic functionalities, the high elasticity of the chains, and the enlarged free volumes between the polymeric chains, that all contribute to the enhancement of the swelling capability of superabsorbent hydrogels. These exceptional attributes have endowed them to be an alternative to conventional hydrogels in various applications. In view of the importance of this class of absorbent material and their diverse appliances, this review deliberates the experimental methods for characterizing superabsorbent polymers, including the officially accepted industrial measurements of their unique attributes, namely, swelling among others. In addition, the review highlights recent advances in the field of superabsorbent polymers encompassing nanofiltration, heat resistance, and absorbency, drug delivery, disposable hygiene products, nanomedicines, and the removal of heavy metals from wastewater and agriculture domains. [ABSTRACT FROM AUTHOR]

Agricultural sustainability is essential to enhance food and water security, particularly in the context of climate change. In the recent past, applications of hydrogels in agriculture have received substantial attention among researchers as well as among farmers. This review elaborates on various aspects of hydrogels such as classifications, ideal properties for agricultural application, and interaction mechanisms with soil and plants. The experimental methods for determining hydrogel properties were given specific attention as properties such as swelling, retention, slow release, and degradation are of vital importance to agricultural sustainability. The studies conducted over the years on the effect of hydrogel application on different crops are reviewed. Several hydrogel studies demonstrate significant improvement in water consumption, water use efficiency, crop growth and yield parameters. The review looks into hydrogel degradation mechanisms in soil and also the 'test methods' for assessment of biodegradation. The gap areas in research on hydrogels and agricultural sustainability have also been identified. The need for developing a framework for the evaluation of the suitability of hydrogel for agricultural applications has been brought out. The review would encourage further research on enhancing the ideal properties of hydrogel and synthesizing with natural polymers. The use of hydrogel in agriculture for controlled nutrient release could be an alternative to conventional release methods for fertilizers and pesticides, thereby reducing the environmental footprint. The reduction in water footprint in major crops such as paddy and wheat through hydrogel might establish a shift towards sustainable irrigation practices if adopted on a large scale. Integrating innovative solutions with environmental-friendly hydrogels in the coming decades will contribute to the pursuit of achieving sustainable development goals. [ABSTRACT FROM AUTHOR]