Formation and stability of nano-emulsions prepared using the phase inversion temperature method

Formation of O/W nano-emulsions has been studied in water/(C) over bar (12)(E) over bar (4)/oil systems by the phase inversion temperature emulsification method. Emulsification was carried out at the corresponding HLB (hydrophilic-lipophilic balance) temperature, and then the emulsions were cooled fast to 25 degreesC. The influence of surfactant concentration and oil solubility on HLB temperature, nano-emulsion droplet size, and stability has also been studied. Droplet size was determined by dynamic light scattering, and nano-emulsion stability was assessed, measuring the variation of droplet size as a function of time. The results obtained showed that the breakdown process of nano-emulsions studied could be attributed to Ostwald ripening. An increase of nano-emulsion instability with the increase in surfactant concentration and oil solubility was also found.