Preparation of Stable Microemulsions with Different Droplet Size

Microemulsion is a widely used technique for preparing nanoparticles. The droplet size in stable microemulsions is a key parameter for limiting the size and shape of the formed nanoparticles. In this paper, the stable microemulsions were synthesized by two titration methods, the water titration method and the co-surfactant titration. Six reagents with different HLB were used as surfactants, including Span-80, E-1302, EL-10, MOA-9, Triton X-114 and OP-10. Quasi ternary phase diagrams of O/W and W/O microemusions with different surfactants were established according to the composition of surfactant, co-surfactant, oil and water. The size of the microemulsions droplets was characterized by using Zetasizer Nano S90. Within the stable micromulsions region, the droplet size was systemically controlled from 1 nm to 120 nm by changing different surfactants and controlling the quality ratio of components. A complex dependence of the droplet size on the water to surfactant ratio and the co-surfactant to surfactant ratio was established. In the stable microemulsions region, the droplets size increases dramatically with increased the water to surfactant ratio and the larger droplet size is obtained with increasing the co-surfactant amount.