Thermotropic and lyotropic properties of n-alkyl-β-D-glucopyranoside surfactants

Abstract

We have studied the thermotropic and lyotropic phase behaviour of di †erent monoalkyl glycosides using polarizing microscopy, di †erential scanning calorimetry and rheology. The dependence of the liquid crystal transition temperature and mesophase formation on the chain length of the hydrophobic tail has been studied. The melting transition for each of the dry alkyl-glycosides corresponds to one or two solidÈsolid transitions, a solidÈliquid crystalline transition and a liquid crystallineÈliquid isotropic transition. The lyotropic behaviour follows the classical pattern established for the surfactants. In the system (X \ 8, 10)Èwater, the C X G 1 mesophases observed with increasing the concentration are a hexagonal phase, a cubic phase and a lamellar phase. Caused by the strong kinetic hindrance, the cubic and hexagonal phases for the system C 10 G 1 (n-decylare only visible by polarization microscopy experiments. Rheological oscillation b-D-glucopyranoside)Èwater experiments permit detection of phase transition. In the low-frequency range the rheological data are consistent with the simple Maxwell model.

Solid-state phase behaviour of dodecylglycosides

“…This peak coincides with a transition reported in the literature, alternatively referred to as a Ôsolid-solid transitionÕ, Ôloss of waterÕ or a Ôpre-transitionÕ. 16,17 When the precipitate is analysed in a sealed pan, on the other hand, the thermogram contains a considerably more symmetric peak at 49°C, whereas the transition at 80°C is not observed (Fig. 6, Table 2).…”

“…3,4,[15][16][17] Additional transitions (referred to as Ôpre-transitionsÕ or Ôsolid-solid transitionsÕ) have been observed at 52-63°C. 16,17 However, these transitions have not been investigated in any detail and their relation to phase structure and possible loss of water of crystallisation has not been elucidated. Therefore, the present study uses a combination of X-ray techniques and calorimetry in order to correlate phase behaviour with phase structure in systems where the amount of water is rigorously controlled.…”

Aggregation behaviour of n-alkyl-β-d-glucopyranoside+water+alcohol mixtures

“…Among the very large number of additives revealed by a literature survey [1], alcohols hold a special place, being by far the most frequently used. Considering the surfactant-class of n-alkyl-␤-d-glucopyranosides (C X G 1 ) the application of cosurfactants is cogent necessary to generate microemulsions [2][3][4][5][6][7][8][9].…”

Acoustical Spectroscopy of Carbohydrate Aqueous Solutions: Saccharides; Alkyl Glycosides; Cyclodextrins. Part II. Association and Complexation

“…Besides synthesis optimization, most work has been devoted to phase diagrams and the structure of different phases of alkyl glycoside solutions (Nickel et al, 1993;Platz et. al., 1995;Bonicontro et al, 1996;Nilsson et al, 1996;Bonicelli et al, 1998;Schulte et al, 1999;Häntschel et al, 1999;Bogusz et al, 2000). The kinetics of self-aggregation, however, has been far less regarded.…”