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Aggregation behavior of a model ionic liquid surfactant in monosaccharide+water solutions

Chen, Yujuan, Zhao, Yang, Chen, Jing, Zhuo, Kelei, Wang, Jianji
Journal of colloid and interface science 2011 v.364 no.2 pp. 388-394
aqueous solutions, arabinose, energy, fluorescence, galactose, glucose, hexoses, ionic liquids, ionization, light scattering, nuclear magnetic resonance spectroscopy, pentoses, physicochemical properties, salts, surfactants, xylose
Alkylimidazolium salts are a very important class of ionic liquids (ILs). The ILs containing long alkyl chains are a kind of model surfactants. In this paper, the aggregation behavior of 1-decyl-3-methylimidazolium chloride ([C₁₀mim]Cl) was investigated for the first time in aqueous monosaccharide (glucose, galactose, xylose and arabinose) solutions by conductivity, fluorescence, NMR and dynamic light scattering (DLS). Thus a series of physico-chemical parameters for the aggregation of [C₁₀mim]Cl—the critical aggregation concentration (CAC), ionization degree of the aggregates (α), the standard Gibbs energy of aggregation (ΔGₘ ⁰), and the aggregation number (N) were derived from the experimental data. The results show that addition of small amounts of monosaccharides in aqueous solution can cause a variation in aggregation properties of the IL. The CAC values decrease with increasing molality of monosaccharides. In particular for different kinds of monosaccharides, we found that the CAC values are in the order: glucose>galactose (hexoses), xylose>arabinose (pentoses); xylose>glucose (1e2e3e4e), arabinose>galactoses (1e2e3e4a). These trends may be attributed to the slight difference in the stereo-structure of monosaccharide molecules. Finally a mechanism for the interaction of these monosaccharides with [C₁₀mim]Cl was proposed.