Highly stable concentrated nanoemulsions by the phase inversion composition method at elevated temperature.

Area of Science:

• Colloid and Surface Science
• Materials Science
• Chemical Engineering

Background:

• Nanoemulsions are thermodynamically stable systems with droplet sizes typically below 200 nm.
• The phase inversion composition (PIC) method is a common technique for producing nanoemulsions.
• Paraffin oil's high viscosity presents challenges in forming fine nanoemulsions.

Purpose of the Study:

• To investigate the effect of preparation temperature on oil-in-water nanoemulsion formation using the PIC method.
• To characterize the droplet size, size distribution, and stability of nanoemulsions.
• To assess the feasibility of using PIC method for highly viscous oils.

Main Methods:

• Oil-in-water nanoemulsions were prepared using water, Span 80-Tween 80 surfactants, and paraffin oil.
• The phase inversion composition (PIC) method was employed at temperatures ranging from 20 to 70 °C.
• Droplet size, size distribution, and viscosity were measured at different volume fractions (φ).

Main Results:

• Nanoemulsions with droplet diameters ranging from 10.3 μm to 51 nm were formed by increasing temperature from 20 to 70 °C.
• Nanoemulsion viscosity increased with droplet volume fraction (φ), while droplet size remained relatively constant.
• Stable size distribution (unchangeable for >5 months at φ ≤ 0.5) was achieved.
• Elevated temperatures facilitated the dispersion of highly viscous paraffin oil, enabling monodisperse nanoemulsion production.

Conclusions:

• The PIC method at elevated temperatures is effective for producing stable oil-in-water nanoemulsions with paraffin oil.
• The resulting nanoemulsions exhibit excellent stability against Ostwald ripening due to low oil solubility.
• These highly stable nanoemulsions hold significant potential for diverse practical applications.