Synthesis of cross-linker devoid novel hydrogels: Swelling behaviour and controlled urea release studies

Hydrogel incorporated fertilizers are most challenging materials in agriculture industries, because of their soil conditioning properties and potential of sustainable release of fertilizer. Polyacrylamide based biocompatible, non-toxic and environmentally benign polymeric hydrogels were synthesized by using acrylamide (AM) and N-hydroxymethyl acrylamide (NHMA) as monomers and potassium persulfate (KPS) as an initiator. Further modification was carried out with incorporation of urea into the hydrogel at the time of synthesis. Eight different formulations of hydrogel without using any cross-linking agent were synthesized by varying the ratio of NHMA in first four grades and used fixed amount of urea in next four grades respectively. These grades were characterized by using FT-IR, SEM, TGA and XRD. In this article, the swelling properties and equilibrium swelling ratio were predicted at different pH and temperature. Also the release of urea from urea incorporated hydrogel was studied and analyzed through UV-vis spectroscopy. Prediction of the possibility of using these hydrogels in agriculture fields is the main objective of this work.