Controlling the Stability and Rheology of Copolyol Dispersions in Fatty Alcohol Ethoxylate (AEO9)-Stabilized Multiple Emulsions

The stability and rheology of water-in-oil-in-water (W/O/W) emulsions stabilized by ABIL EM 90 (water-in-oil) and fatty alkoxy ethylene ether-AEO9 (oil-in-water) were investigated. The addition of salt (NaCl) at varying concentrations into the internal aqueous phase formed a strong network that changed the stability of multiple emulsions. W/O/W emulsions were further modified by varying the disperse phase ratio, concentration of AEO9, and shear forces. Remarkably, the thickening behavior was induced into W/O/W emulsions when the concentration of NaCl (0-0.2 wt %), dispersed phase (phi = 0.20-0.33), and shear forces (3000-5000 rpm) varied in the emulsion formulations. An increase of up to 3 orders of magnitude in the viscoelasticity (storage modulus and yield stress) of multiple emulsions was achieved. Multiple emulsion droplets showed strong resistance to coalescence during long-term shelf storage by the formation of a gel-like barrier at the interface. These emulsions products are, therefore, highly versatile formulation with a high degree of stability.