Enhancing Nutrient Utilization Efficiency and Longevity in Agriculture: Isothiocyanate‐Modified Bio‐Based Polyurethane Coatings for Sustainable Controlled‐Release Fertilizers

ABSTRACT The damage of traditional coated controlled‐release fertilizers (CRFs) can deeply decrease their nutrient release longevity, and is not conducive to promoting sustainable development. Therefore, developing coating materials with superior elasticity is an effective way to enhance the release characteristics of CRFs. In this study, we utilized isothiocyanate and polyethylene glycol as elastomer modifiers to introduce disulfide bonds into castor oil‐based bio‐based coating materials for polyurethane, aiming to improve the damage resistance and mechanical behavior of polyurethane coating material. Then, the coated CRF modified with isothiocyanate was prepared (MCRF), which had remarkable elasticity. The elongation at break of MCRF increased from 76.74% to 144.07 %. Meanwhile, the controlled release longevity of MCRF was prolonged from 49 to 77 days compared with CRF, representing a 57% increase. Molecular dynamics studies revealed that the diffusion behavior of urea molecules was significantly inhibited in the polymer system after cross‐linking by the elastomer modifiers. The formation of the cross‐linked network increased the connection points between polymer chains, a denser system structure was formed, and restricted the movement of urea molecules. This study provides valuable support and reference for the slow release of nutrients for CRFs, and is committed to promoting green and sustainable production.