Efficient construction of polydopamine multi-compartment microcapsules for pesticide-fertilizer co-encapsulation

Pesticides and fertilizers are typically used in traditional agriculture. However, their incompatibility often causes efficacy reduction and environmental risks. Herein, we propose a new strategy for preparing polydopamine (PDA) multi-compartment microcapsules. The PDA nanocapsules can be synthesized through emulsion polymerization, with spherical morphology and a particle size range of 30–100 nm, which are used as shell materials to fabricate PDA multi-compartment microcapsules via spray drying technology. The as-prepared spherical microcapsules obtain a particle size range of 0.8–3.0 μm and good dispersibility, and can separately encapsulate the oil-soluble avermectin (AVM) and water-soluble urea to form Urea@AVM@PDA. In addition, these microcapsules can achieve controlled release of AVM and urea under different temperatures, pH, and NIR conditions, with good adhesion ability. The Urea@AVM@PDA also exhibits a lower LC 50 (18.416 μg/mL) than avermectin emulsifiable concentrate (AVM-EC, 23.923 μg/mL), and causes 36.67 % higher mortality of Plutella xylostella after ultraviolet treatment, which confirms the ultraviolet resistance of PDA shell layers. Furthermore, the potting experiment proves the Urea@AVM@PDA can promote pumpkin seedling growth.