【Frontiers in HaiChuan Chemical Technology】Researchers have developed a nano-SiO2-modified superhydrophobic polyurethane coating for the controlled release of urea

Thread Content

Researchers have developed a nano-SiO2-modified superhydrophobic polyurethane-coated urea for controlled release. Recently, the Fertilizer and Fertilization Technology Innovation Team at the Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, addressed industry-related issues such as the short nutrient release period caused by the poor hydrophobicity of polyurethane-coated controlled-release fertilizer films, and successfully created a nano-SiO2-modified superhydrophobic polyurethane-coated urea for controlled release. The water contact angle (WCA) of this new type of fertilizer film layer is as high as 165.44°, and its controlled-release period can reach up to 61 days. The relevant research findings have been published in the journal ACS Omega (JCR Q1, IF 4.3). In this study, SiO₂ with different particle sizes was used as the core material. 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS) was first employed to graft it onto the surface of SiO₂ via a two-step process of alcoholysis followed by condensation, thereby effectively improving the dispersibility of SiO₂ and successfully preparing FAS-SiO₂ modified superhydrophobic materials. Secondly, the effects of three processing methods—surface coating, blending, and outer-layer blending—on properties such as the surface energy, microstructure, roughness, and water contact angle of the superhydrophobic nano-SiO₂-coated urea film layers, as well as on the fertilizer’s controlled-release period, were systematically studied. It was found that the surface coating method enables the superhydrophobic properties of FAS-SiO₂ to be fully utilized; this method can significantly reduce the surface energy of the film layer, create stable micro/nano-superhydrophobic structures, result in a water contact angle of up to 158.24°, and ensure excellent stability of the film layer. This approach successfully overcomes the key technical challenge of easy peeling off of nanocoatings. Finally, the study found that FAS-SiO₂ particles of different sizes had a significant impact on the performance of the membrane layer and the duration of controlled release. Among them, polyurethane-coated fertilizers modified with 20 nm FAS-SiO₂ exhibited the best overall performance, with the controlled release period extending by 21 days compared to conventional polyurethane-coated urea. This research achievement not only provides a solid theoretical foundation for the development and application of nano-controlled-release fertilizers, but also offers important technical support for accelerating the upgrading of the coated fertilizer industry and facilitating product innovation, which is of great significance for promoting the green and efficient development of modern agriculture.