Phase behavior, transport, diffusion and structural parameters of nonionic surfactants microemulsions

In this study we explored the water + propylene glycol/sucrose esters/benzaldehyde + ethanol systems in order to determine the one phase microemulsion regions. The mixing ratios (w/w) of water/propylene glycol and benzaldehyde/ethanol equal to 2 and 1, respectively. The pseudoternary phase behavior at 27, 37, and 45 °C was explored to determine the effect of temperature on the amount of solubilized water in the microemulsions. For each system investigated the total area of the one phase microemulsion region was determined. It was found that minor changes in the surfactant structure suffice to provoke a considerable change in the total monophasic area of the system. A one phase microemulsion region extending from the oil-rich region to the water-rich corner was observed in systems based on sucrose laurate and sucrose myristate at 27 °C. The sucrose laurate based system was investigated using electrical conductivity; dynamic viscosity and pulsed gradient spin echo-nuclear magnetic resonance. It was found that the electrical conductivity increases as the water volume fraction increases. Viscosity decreases with the increase in the water volume fraction. Nuclear magnetic resonance measurements confirm a progressive transformation of the water-in-oil to bicontinuous and inversion to oil-in-water microemulsions occurs upon dilution with water. The interfacial area occupied by the surfactant and cosurfactants was estimated.