| Summary: | 博士 === 靜宜大學 === 應用化學研究所 === 94 === In this study, the oil in water emulsions were prepared using mineral oil and jojoba oil in the oil phase, the glycerin and water in the aqueous phase, and the nonionic surfactants such as Span80, Tween80, Brij97 and Brij92 as emulsifiers, in which jojoba oil and glycerin as humectants. The experiment first discussed the parameters of manufacturing procedures which influence the mean droplet size and stability of emulsions. The experiment results showed that the optimum manufacturing procedures for nano-emulsion were: adding ten grams of three optimized blend emulsifiers (Span80+Tween80, Span80+Brij97, or Brij97+Brij92) in oil phase separately, preheating the oil and aqueous phases for fifteen minutes, emulsification at 70℃ or 80℃, homogenization speed at 1000rpm, emulsification for thirty minutes, hydrophilic-lipophilic balance, HLBAB=10.72, and natural or iced cooling down to 25℃. The mean droplet diameter of the moisture nano-emulsions thus prepared were smaller than 100nm, and the nano-emulsions can stabilize for at least two months without separation at ambient storage.
Second, the experiment studied the physical properties such as mean droplet diameter, viscosity, surface tension, and contact angle of the nano-emulsions suitably applied to the spray type cosmetics. Four batches of oil in water nano-emulsions were prepared, each with a different mixed emulsifier. Initial mean droplet diameter of the nano-emulsions were measured to be, in order: Tween80+Brij92 (250 nm) > Span80+Brij97 (77 nm) > Span80+Tween80 (61 nm) > Brij97+Brij92(50 nm). The nano-emulsions’ viscosities were all below 10 cP, the low viscosity fluids, at shear rates above 100 sec-1. The variability in surface tension of the nano-emulsions, as represented by the standard deviation, was ranked in the order: Tween80+Brij92 > Span80+Brij97 > Span80+Tween80 > Brij97+Brij92. A lesser variation in surface tension represents a greater stability of the nano-emulsions. The contact angles between the nano-emulsions and the common packing materials such as PET, PMMA, PP, PVC, TEFLON and glass were measured and the results showed that the hydrophobic TEFLON material presented poor moistness and affinity, while the hydrophilic glass materials presented the best moistness and affinity.
Third, the experiment discussed the effects of blending mixed emulsifiers and gum arabic on the mean droplet diameter, zeta potential, and conductivity of the nano-emulsions. The results showed that, by means of the special “wattle blossom” structure of the gum arabic along with the mixed emulsifiers adsorbing onto the oil-water interfaces, the mean droplet diameter of the emulsions would be reduced effectively and the nano-emulsions would be obtained. On the other hand, low zeta potential was observed for non-charge non-ionic type emulsifiers. In the presence of mixed emulsifiers and gum arabic, the zeta potential of the nano-emulsions prepared by Span80+Tween80 and Span80+Brij97 will be much easily affected by pH than those prepared by Brij97+Brij92 and Tween80+Brij92. In the range pH6~8, the zeta potential will down sharply and then up again. With the addition of gum arabic, the conductivity of the emulsion will increase significantly and the degree will be enhanced in the alkaline environment than in the acidic environment which means that the emulsion would be much hydrophilic in the alkaline environment. The above nano-emulsions emulsification formulate along with active ingredients can deliver efficiently through the skin, and thus enhance penetration and absorption of actives which can be applied for skin care cosmetics or pharmaceutics.
|
|---|
