Preparation and Characterization of Cycloalkanol/Water Emulsion Using α-Cyclodextrin as an Emulsifier

Abstract

We examined the preparation and characterization of cycloalkanol/water emulsions using α-cyclodextrin (α-CD) as an emulsifier. Emulsions were prepared by mixing α-CD, cycloalkanol, and water using a vortex mixer. The mechanism of emulsification was investigated with some physicochemical techniques. From phase diagrams of cycloalkanol/α-CD/water systems, the emulsion phase extended as the carbon number of cycloalkanols increased. Furthermore, it was thought that the coexistence of precipitated cycloalkanol/α-CD complexes were necessary for formation of the emulsion. However, the precipitated complexes did not have surface activity. From observation using a polarized light microscope, it was suggested that the precipitated complexes were formed at the oil-water interface and supplied to the continuous phase. We concluded that cycloalkanol/water emulsions using α-CD were stabilized by precipitated complexes that exist on the droplet surface and the continuous phase, and these emulsions were a type of Pickering emulsion.

Keywords:

• α-Cyclodextrin
• cycloalkanol
• Pickering emulsion
• rheology

This work was supported in part by “High-Tech Research Center” Project for Private Universities: matching fund subsidy from MEXT (Ministry of Education, Culture, Sports, Science and Technology), 2007 and Nihon University Research Grant for 2007.

Notes

Part of the special issue, Surface and Colloid Chemistry Without Borders: An International Festschrift for Professor Per Stenius on the Occasion of His 70th Birthday.