Sustainable and Biodegradable Copolymers from SO2 and Renewable Eugenol: A Novel Urea Fertilizer Coating Material with Superio Slow Release Performance

To enhance SO2 utilization, improve fertilizer use efficiency, and minimize the negative environmental impact, the novel slow release sulfur-containing urea fertilizers with good biodegradation performance were developed by coating with the sustainable poly(eugenol sulfone) derived from renewable eugenol and SO2. The poly(eugenol sulfone) was synthesized by a simple free radical polymerization under mild conditions, and structural features of the synthesized copolymers were studied by various characterization techniques. Characterization results revealed that the copolymers exhibited the strict alternating copolymerization structures containing O=S=O. A set of systematically designed experiments were carried out to determine the influences of the amount of initiator, reaction time, and reaction temperature on the molecular structure, release, and biodegradation behavior of the coated fertilizers. The obtained results proved that the coated fertilizers showed excellent release and biodegradation features. Moreover, the release and biodegradation rate of the coated fertilizers can be adjusted by changing the molecular weight of poly(eugenol sulfone). In addition, the kinetic study on the slow release characteristics of poly(eugenol sulfone)-coated fertilizers showed that the best fitting effect was obtained by the Ritger-Peppas equation. This work offers a simple and useful strategy for designing sulfur-containing urea fertilizers with excellent slow release and biodegradation performance and provides a new route for sulfur recycling. In the future, the fertilizer will be deeply tested to evaluate their impact on plant growth, chemical, and biological soil properties.