Surfactant concentration also played a major role in
droplet size of nanoemulsion. Increasing surfactant concentration
resulted in decrease in droplet diameter (Fig. 3).
Droplet size of CF1 formulation with 6% surfactant concentration
after sonication for 30 min was found to be
254 nm, whereas CF2 formulation was 96 nm. Mean
droplet diameter of the CF3 nanoemulsion has lowest
droplet diameter of 65 nm after a sonication period of
30 min. Droplet size distribution of CF3 nanoemulsion
formulation after being subjected to ultrasonic emulsification
for 30 min is shown in Figure 4. Gibbs free energy
upon formation of nanoemulsion is greater than zero and
hence they are thermodynamically unstable systems and
process of nanoemulsion formation is non-spontaneous.
Surfactants acts as emulsifiers and serve the process by
lowering the free energy required for the preparation of
nanoemulsion by decreasing interfacial tension at oil/water
interface.34
3.2.2.