*3.2. Pseudo-Ternary Phase Diagrams*

Pseudo-binary solutions of surfactant and oil in all ratios for the surfactant mixtures for dilution-line 1 to dilution-line 8 exhibited two phases of Winsor I-type phase behavior on standing for 30 min, but formed turbid mixtures following vortex mixing for 30 s at 800 rpm. Dilution-line 9 or ratio 9 resulted in a transparent and kinetically stable, isotropic system which exhibited Winsor IV-type behavior for up to 12 months at room temperature (22 ◦C). The droplet sizes of these ratio mixtures gradual increased as the proportion of flaxseed oil used increased while surfactant content decreased. The surfactant to oil ratio for the 9:1 pseudo-binary solution resulted in emulsions with the smallest droplet size and lowest PDI of all ratios tested. Both a nanoemulsion and microemulsion region was observed along dilution-line 9 for all three surfactant mixtures tested. Five distinct regions were formed viz., a nanoemulsion that is transparent Winsor IV, milky Winsor IV, i.e., cloudy isotropic mixture, translucent Winsor I, II and III, milky Winsor I, II and III in addition to a gel/semisolid region. Ratio 9 formed clear isotropic and transparent nanoemulsions with up to 35% *v*/*v* water addition for surfactant-mixture 1 as depicted in Figure 3, up to 20% *v*/*v* water for surfactant-mixture 2 as depicted in Figure 4 and only up to 5% *v*/*v* for surfactant-mixture 3 as depicted in Figure 5. While the nanoemulsion region area decreases as the ethanol content in the surfactant mixture increases, the milky isotropic and two or three-phase regions of the o/w emulsion also exhibit an increase in area whereas the gel region decreases in size with an increase in ethanol content, as the interfacial film is flexible, thereby solid structures are disrupted and the fluid phase areas increase in dimension. The dilute aqueous isotropic regions of cloudy o/w emulsions may be appropriate for an immediate release effect, due to the ease of dispersion of this phase in aqueous media [45]. Electrical conductivity measurements along dilution-line nine from the pseudo-binary solution of the surfactant/oil phase to the water vertex suggest that phase-inversion of system from a w/o to an o/w nano or microemulsion occurs at a specific point if not in a range of values as summarized in the titration chart followed in Table 1. The surfactant mixture for the S1 mixture exhibited the largest nanoemulsion region in the phase diagram and resulted in the production of the largest number of kinetically stable nanoemulsions following addition of water.
