Water-Dependent Upcycling of Eco-Friendly Multifunctional Nanocompartmentalized Films

Nanocompartmentalized films are promising materials for different applications, including biomedical, food, and agricultural fields. Herein, a new concept to prepare such multifunctional films is reported. Aqueous dispersion of nanoparticles based on Ecovio loaded with an active compound (Neem oil as concept proof) is first synthesized by single emulsion-solvent evaporation technique using poly(vinyl alcohol) (PVA) as a surfactant. Then, this dispersion is used to prepare films by casting. The feasibility of upcycling (i.e., deconstruction and reassembly of the films) is obtained through a water-dependent dynamic phenomenon, where the PVA acts as polymer matrix or surfactant depending on the hydration of the surrounding medium (dry or wet conditions). Nanocompartmentalized films demonstrate improved mechanical performance and reduced transmittance in UVA and UVB spectra, while the nanoparticles (wet condition) show superior stability (more than 9 months). The proposed method allows preparing films with high compartmentalization efficiency that can be used, for instance, as insect-repellent packaging. Just by adding the films in water, the aqueous dispersion of nanoparticles can be used for controlled release of pesticides, leading to high added value material that fits the circular economy.