Double-Shell Lignin Nanocapsules Are a Stable Vehicle for Fungicide Encapsulation and Release

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Department of Chemistry; Department of Chemical Engineering


Industry is increasingly turning to biobased and environmentally benign materials for use in high-value applications. Kraft lignin's low cost and inherent properties, such as its easily tunable amphiphilic nature, adsorption capacity, and natural cross-linking tendency, make it suitable for use as a raw material for high-value nanomaterials. To support that need, this paper describes the synthesis of innovative, double-shelled lignin nanocapsules from hardwood kraft lignin, their performance towards encapsulating a fungicide, and effectiveness at controlling its release. The recovered lignin was dissolved without further modification in tetrahydrofuran and inserted dropwise into a water/ethanol solution containing sacrificial surfactant templates. Monodispersed, hollow, double-shell nanocapsules were produced via a two-step self-assembly. The water/ethanol solution acted as a nonsolvent while simultaneously providing strategic sites for controlled-size production. The shells of the nanocapsules were cross-linked with biodegradable maleic anhydride to bolster the structural stability. The average hydrodynamic diameter of the particles was 241.8 ± 33.3 nm, and these structures were stable in water for a period of eight months. The specific surface area of kraft lignin increased by 4-fold in the double-shell nanocapsule form. The nanocapsules were loaded with propiconazole at an entrapment efficiency of 56.1%. This system could represent an effective method to enable biologically activated, controlled release of fungicides.

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© 2020 American Chemical Society. Publisher’s version of record:

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ACS Sustainable Chemistry and Engineering