Temperature-responsive hydrogel prepared from carboxymethyl cellulose-stabilized N-vinylcaprolactam with potential for fertilizer delivery

The growth of plants is highly dependent on sufficient water and suitable fertilizer nutrients, but the soil often loses moisture and the fertilizers are low efficiency. To address this issue, the temperature-responsive hydrogels were developed using the N-vinylcaprolactam (NVCL) dispersed in water through the emulsification of carboxymethyl cellulose (CMC) and acrylamide (AM), and urea was loaded into the hydrogel as a fertilizer. The amount of CMC and monomer have an effect on the structure, mechanical properties, swelling ability, and temperature sensitivity of the hydrogel. Therefore, the maximum swelling ratio of the hydrogel can reach 2056 % with the increasing hydrophilic groups, and the hydrogel exhibits a deswelling behavior as the temperature rises to higher than LCST due to the temperature responsiveness. Moreover, the fertilizer can rapidly release when the temperature is higher than LSCT, and exhibits similar release behavior in water and soil. Thus, the temperature-responsive hydrogel shows a great potential application for the controlled release of water and fertilizer in agriculture and forestry.