On the preparation and characterization of nanoemulsions produced by phase inversion emulsification

Formation, appearance, particle size and viscosity of n-undecane in water (nano)emulsions prepared by the phase inversion method using non-ionic surfactants (Igepal, Brij) were investigated. The effects of the HLB value, oil-in-water ratio (5/95 to 30/70), surfactant type and its concentration (3 and 5%) on the physico-chemical characteristics of emulsions were studied. Emulsions were characterized by visual and microscopic observations and the particle size and distribution as well as emulsion viscosity were determined. The results showed that all the variables mentioned above considerably influenced both the particle size and the viscosity. The smallest particle sizes (lower than 250 nm) and the best emulsion stability were determined at optimum HLB of 10.5 for all the studied oil-in-water ratios, both types and concentrations of surfactants. Typically, the emulsion droplets prepared with Igepals were bigger than those prepared with Brij systems.

Particle sizes of O/W (nano)emulsions determined immediately after the preparation. Influence of the HLB value (3% Igepal surfactant). Absent values of z-average particle diameter at HLB 10 (O/W 5/95) and 9.5 (O/W 5/95, 10/90) indicate impossibility to form the O/W emulsions under these conditions.Figure optionsDownload as PowerPoint slideHighlights
► n-Undecane/water nanoemulsions were prepared using phase inversion.
► Nonionic surfactants (Igepal, Brij) were used at the O/W range of 5/95 to 30/70.
► The smallest emulsion droplets arose near the transition point, at HLB of 10.5.
► Igepals provided bigger droplets than Brijs in all studied O/W ratios and HLBs.
► Nanoemulsions based on Brijs were more time stable, for 121 days at room temperature.