Preparation and characterization of polyurethane-/MMT nanocomposite-coated urea as controlled-release fertilizers

A new nanocomposite coating was synthesized by MMT and polyurethane for controlled-release fertilizers (CRFs). The structure and properties of samples were characterized. The nutrient release behavior of nanocomposite-coated fertilizers (MPUs) and polyurethane-coated fertilizers (PU) in water and in soil were determined. SEM and TEM exhibited good dispersion of MMT lamellae in the MPU coatings. The results also showed that the water contact angle of the MPU coating was greatly improved, the water absorption was reduced by 65.7%, and the coating porosity was reduced by 30.0%. In addition, MPUs exhibited longer nutrient release longevity than that of PU (26 days), especially MPU with 5% MMT (90 days). Therefore, MPUs with excellent properties can provide information for the development of CRFs.