Highly dilute phases with alkylmonoglucopyranosides

The Krafft points of alkyl α and β-D-glucopyranosides decrease monotonously with chain length. The crystals are transformed into condensed lamellar phases on addition of longer-chain alcohols, even at temperatures below the Krafft points of the binary systems. Swelling is never observed in the ternary systems. Using the model system decyl a-D-glucopyranoside/decanol/ water, it is shown that highly swollen lamellar phases with brilliant colours are formed when traces of anionic surfactants (sodium decylsulphate SDeS, sodium dodecylsulphate SDS, calcium dodecylsulphate CDS) are added. The iridescent phases are extremely temperature-stable but highly sensitive to electrolyte addition (NaCl). Because of their lower Krafft points, the alkyl β-D-glucopyranoside and α/β mixtures are even more stable at lower temperatures. Cationic surfactants (decyl trimethylammonium bromide) are less suited. Iridescent phases are formed at 30 °C with decyl α-D-glucopyranoside and alcohols from hexanol to pentadecanol. Alkylglucosides with still longer chains need higher temperatures (dodecyl α-D-glucopyranoside and dodecanol (50 °C) or decanol (30 °C)).