National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, National Engineering & Technology Research Center for Slow and Controlled-release Fertilizers, College of Resources and Environment , Shandong Agricultural University , Taian , Shandong 271018 , China.
Department of Soil and Water Science, Tropical Research and Education Center, IFAS , University of Florida , Homestead , Florida 33031 , United States.
ACS Nano. 2019 Mar 26;13(3):3320-3333. doi: 10.1021/acsnano.8b09197. Epub 2019 Mar 7.
Although commercialized slow-release fertilizers coated with petrochemical polymers have revolutionarily promoted agricultural production, more research should be devoted to developing superhydrophobic biopolymer coatings with superb slow-release ability from sustainable and ecofriendly biomaterials. To inform the development of the superhydrophobic biopolymer-coated slow-release fertilizers (SBSF), the slow-release mechanism of SBSF needs to be clarified. Here, the SBSF with superior slow-release performance, water tolerance, and good feasibility for large-scale production was self-assembly fabricated using a simple, solvent-free process. The superhydrophobic surfaces of SBSF with uniformly dispersed FeO superhydrophobic magnetic-sensitive nanoparticles (SMNs) were self-assembly constructed with the spontaneous migration of FeO SMNs toward the outermost surface of the liquid coating materials ( i.e., pig fat based polyol and polymethylene polyphenylene isocyanate in a mass ratio 1.2:1) in a magnetic field during the reaction-curing process. The results revealed that SBSF showed longer slow-release longevity (more than 100 days) than those of unmodified biopolymer-coated slow-release fertilizers and excellent durable properties under various external environment conditions. The governing slow-release mechanism of SBSF was clarified by directly observing the atmosphere cushion on the superhydrophobic biopolymer coating using the synchrotron radiation-based X-ray phase-contrast imaging technique. Liquid water only contacts the top of the bulges of the solid surface (10.9%), and air pockets are trapped underneath the liquid (89.1%). The atmosphere cushion allows the slow diffusion of water vapor into the internal urea core of SBSF, which can decrease the nutrient release and enhance the slow-release ability. This self-assembly synthesis of SBSF through the magnetic interaction provides a strategy to fabricate not only ecofriendly biobased slow-release fertilizers but also other superhydrophobic materials for various applications.
虽然商业化的石油基聚合物包膜控释肥料极大地促进了农业生产，但我们仍需要更多的研究来开发具有超疏水性能的生物聚合物包膜，以实现可持续且环保的控释肥料。为了推动超疏水生物聚合物包膜控释肥料（SBSF）的发展，我们需要阐明其控释机制。在这里，我们使用简单的无溶剂工艺，自组装制备了具有优异的控释性能、耐水性和大规模生产可行性的 SBSF。通过在反应固化过程中磁场的作用，FeO 超疏水磁性敏颗粒（SMN）在液体涂层材料（即猪脂多元醇和聚亚甲基多苯基多异氰酸酯，质量比为 1.2:1）的最外层自发迁移，从而自组装构建了具有均匀分散 FeO SMN 的 SBSF 的超疏水表面。结果表明，SBSF 的控释寿命（超过 100 天）明显长于未改性的生物聚合物包膜控释肥料，并且在各种外部环境条件下都具有优异的耐用性能。通过同步辐射 X 射线相衬成像技术直接观察超疏水生物聚合物涂层上的大气垫，阐明了 SBSF 的控释机制。只有液体水会接触到固体表面凸起的顶部（10.9%），而气穴会被困在液体下方（89.1%）。大气垫允许水蒸气缓慢扩散到 SBSF 的内部尿素核心，从而减少养分释放并增强控释能力。通过这种基于磁相互作用的 SBSF 自组装合成，为制备环保型生物基控释肥料以及其他超疏水材料提供了一种策略，可应用于各种领域。
