Oil/Water Droplet Formation by Temperature Change in the Water/C_(16)E_6/Mineral Oil System

摘要

Droplet sizes of oil/water (O/W) nanoemulsions prepared by the phase inversion temperature (PIT) method,in the water/C_(16)E_6/mineral oil system,have been compared with those given by a theoretical droplet model,which predicts a minimum droplet size.The results show that,when the phase inversion was started from either a single-phase microemulsion (D) or a two-phase W+D equilibrium,the resulting droplet sizes were close to those predicted by the model,whereas,when emulsification was started from W+D+O or from W+D+L alpha (L alpha = lamellar liquid crystal) equilibria,the difference between the measured and predicted values was much higher.The structural changes produced during the phase inversion process have been investigated by the ~1H-PFGSE-NMR technique,monitoring the self-diffusion coefficients for each component as a function of temperature.The results have confirmed the transition from a bicontinuous D microemulsion at the hydrophile-lipophile balance (HLB) temperature to oil nanodroplet dispersion in water when it is cooled to lower temperatures.