Degradable itaconic acid-based polyurethane with excellent sustained release of urea for agricultural applications

Abstract

Thermoset polyurethanes find applications in various industries due to their exceptional performance resulting from their permanent cross-linked structure. However, thermoset polyurethanes are all obtained by chemical cross-linking, and their permanent network structure cannot be recycled or reprocessed. This results in the waste of non-renewable petroleum resources and environmental pollution. Therefore, preparing polyurethane (PU) from biomass has become a key focus of attention. This study synthesized itaconic acid-based polyols from itaconic acid (IA) and 1-thioglycerol (TG) by a thiol-ene photoclick reaction. Subsequently, we synthesized itaconic acid-based polyurethane materials by adjusting the ratio of soft and hard segments. The materials displayed excellent mechanical and degradation properties, with a maximum tensile strength of 50.61 MPa and a remaining mass of 56.79 % at 126 days for IATG-PUs-3. Urea was coated on itaconic acid-based polyurethane (PU) to facilitate its function as a slow-release fertilizer. The release rate in soil over 30 days was 81.63 %. Based on this, we conducted an indoor potting test to investigate the growth-promoting effect of slow-release fertilizer on Chinese little greens and Little bok choy. It found that covering the plants with a film of IATG-PUUs significantly improved their growth indices. Furthermore, the growth indices of plants covered with an IATG-PU film were higher than those not mulched. This approach presents a practical solution for creating bifunctional membranes with slow-release fertilizer and biodegradation properties.