Dispersion kinetics and release behavior of eugenol from ternary water/eugenol/Poloxamer 407 systems: Toward ecofriendly larvicide formulations

Essential oil–based insecticides are limited by poor water solubility and uncontrolled dispersion in aquatic environments. This study investigates ecofriendly delivery systems based on ternary water/eugenol/Poloxamer 407 (P407) formulations for potential application in Aedes aegypti breeding sites. Emulsions, gel-like emulsions, and gels were prepared and diluted in water to a final eugenol concentration of 90 ppm. Dispersion kinetics, spatial distribution, mechanical energy requirements, and larvicidal efficacy were evaluated by UV–Vis measurements, fluorescence spectroscopy, and controlled agitation experiments. Fluorescence analysis demonstrated that dilution reduced the P407 concentration below its critical micelle concentration, inducing micellar disassembly and release of eugenol into the aqueous phase. Under quiescent conditions, emulsions exhibited faster but spatially heterogeneous dispersion, reaching ~40–60% of the nominal concentration after 120 min, whereas gels displayed slower, diffusion-controlled release with uniform but limited dispersion (