Determination of the binary phase diagram of n-decyl-β-D-glucoside in water

CHED 972

Alison R. Lee,, Christina A. Snyder, Gerald R. Van Hecke, and Kerry K. Karukstis, Department of Chemistry, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711
The aqueous phase behavior of n-decyl-β-D-glucoside, a system that forms lyotropic liquid crystals, was investigated using polarized light microscopy and fluorescence spectroscopy. The fluorescent probe prodan, with emission spectra sensitive to the polarity of its environment, was employed as a means of determining the phases present at a given composition and temperature. Several lyotropic phases - micellar, cubic, lamellar, gel, and crystalline - were detected via polarized light microscopy and found to yield a unique prodan fluorescence emission spectrum. Phases with three-dimensional order (cubic, crystal) or high viscosity (gel) exhibit spectra reflective of the probe partitioned into hydrophobic and/or constrained regions of the microstructures, while lamellar and micellar aggregates exhibit spectra reflecting prodan positioned within the aggregate hydration sphere. Multiphase regions were easily identified via fluorescence spectra that were composites of individual aggregate spectra. A complete binary phase diagram of water and the glucoside was constructed using this approach.