Study on preparation and formation mechanism of n-alkanol/water emulsion using alpha-cyclodextrin.
Surfactants are usually used for the preparation of emulsions; however, some have an adverse effect on the human body such as skin irritation, hemolysis, and protein denaturation, etc. In this study, we examined the preparation and formation mechanism of n-alkanol/water emulsions using alpha-cyclodextrin (alpha-CD) as an emulsifier. Emulsions were prepared by mixing oil and water phases for 4 min at 2500 rpm using a vortex mixer. The mechanism of emulsification was investigated with some physico-chemical techniques. From phase diagrams of n-alkanol/alpha-CD/water systems, the emulsion phase extended as the chain length of n-alkanols and the amount of alpha-CD added increased. Furthermore, the emulsion was not formed in the region where the n-alkanol/alpha-CD complex didn't precipitate; however, the emulsion was formed in the region where the complex precipitated. In addition, it was clear that the emulsions have a yield stress value and correspond to the Maxwell model from rheological measurement. Our experiments clearly showed that the stable emulsions are formed because the precipitated complexes form a dense film at the oil-water interface and prevent aggregation among dispersed phases. Furthermore, it is suggested that the creation of a three-dimensional network structure formed by precipitated complexes in the continuous phase contributes to the stabilization of the emulsion. Thus, we concluded that the n-alkanol/water emulsions using alpha-cyclodextrin were a kind of the Pickering emulsion.
Hashizaki
Kaname
K
College of Pharmacy, Nihon University, Funabashi, Chiba, Japan.
Kageyama
Takashi
T
Inoue
Motoki
M
Taguchi
Hiroyuki
H
Ueda
Haruhisa
H
Saito
Yoshihiro
Y
D000438:Alcohols / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D045703:Emulsifying Agents / Q000737:chemistry*; D008859:Microscopy, Polarization; D009821:Oils / Q000737:chemistry*; D012212:Rheology; D012995:Solubility; D013314:Stress, Mechanical; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction; D047391:alpha-Cyclodextrins / Q000737:chemistry*
D000438:Alcohols; D045703:Emulsifying Agents; D009821:Oils; D047391:alpha-Cyclodextrins; D014867:Water