Stimuli-responsive Ca-alginate-based photothermal system with enhanced foliar adhesion for controlled pesticide release.

For minimizing volatilization and leaching of pesticides, and enhancing their residence time on crop surfaces, we synthesized and characterized a novel intelligent pesticide delivery system. Therein, imidacloprid (IMI) was adsorbed by polydopamine modified kaolin (PK) with high adsorption property through hydrogen bonds. Ca-alginate was used as a structural matrix of the system and a protective shell to hinder the pesticide burst release from PK, and endowed the system with unique pH-sensitive property for IMI release. The amino silicone oil (ASO) coating could bind with the waxy layer of crop leaves by the theory of "similarity-intermiscibility", which increased the adhesion of composite on crop leaves. Moreover, by the excellent light-sensitive property of detonation nanodiamond (DND) and temperature-responsive performance of poly(N-isopropylacrylamide) (PNIPAm), the release of IMI from the functional system could be adjusted by sunlight. Besides, the composite displayed high control efficacy. This novel composite can promote the targeting ability and utilization efficiency of pesticides, thus having a huge potential application prospect in agriculture.