Multi-stimuli responsive cellulose nanocrystal-based microcapsules with enhanced insecticidal efficacy and environmental safety

Sustainable crop protection relies on the development of pesticide formulations characterized by intelligent release performance and high biological safety. However, due to the reliance on costly functional additives and complex synthesis processes, achieving all these multiple functions simultaneously still poses a formidable challenge. Here, we report cost-effective methacrylic anhydride-functionalized cellulose nanocrystals (MCNCs)-stabilized high internal phase Pickering emulsion (IMI@MCNCs-HIPPE) as a template for constructing a smart insecticide system. Through in situ radical polymerization of N, N-Diethyl-2-propenamide (DEAAM), we synthesized IMI@MCNCs-g-DEAAM microcapsules that exhibit multi-stimuli responsiveness (dual-pH responsive and temperature responsive), efficient pesticide encapsulation (96.5%), and a high loading capacity (58.2%). The resultant microcapsules demonstrate sustained and controlled release along with exceptional spreading, adhesion, rainfastness, and photostability on corn and tomato leaves, outperforming the commercial EC (Bisair®). Bioassays against Rhopalosiphum maidis and Tomato leafminers confirmed superior insecticidal efficacy of the microcapsules, while safety assessments on seed germination, soil microbes, and zebrafish indicated excellent environmental compatibility. This research innovatively establishes a sustainable, cost-effective, and multifunctional nanocellulose-based platform, enabling controlled release, precise targeting, and improvement in biological safety, thereby providing critical technical support for sustainable agriculture.