Effect of Alcohols on the Micelle Formation of Nonionic Surfactants in Aqueous Solutions

Abstract

The variation of critical micelle concentrations (CMC) of polyoxyethylene lauryl ethers having various ethylene oxide chain lengths \barn(\barn=6, 11, 20, and 31) on addition of short chain alcohols to the surfactant aqueous solutions was determined at 20 °C. Thermodynamic quantities of micelle formation in methanol– and ethanol–water mixtures and in pure water were obtained in connection with the heat of micelle formation determined by direct calorimetry. Methanol and ethanol showed a CMC-increasing effect only, whereas the addition of n-propanol, n-butanol, and n-pentanol showed a CMC-decreasing effect. The overall CMC-increasing effect is interpreted as being mainly due to the fact that methanol and ethanol weaken the hydrophobic bond. However, the effect also has a secondary effect of lowering the CMC slightly on the polyoxyethylene portion of a surfactant. Several factors are suggested for explaining this secondary effect. The CMC-decreasing effect is explained by a decrease in the free energy of mixing resulting from the solubilization of alcohol molecules into the micelle.

Adsorption and volumetric properties of Triton X-100 and propanol mixtures

“…This statement can explain why there are in the literature controversial opinions dealing with the influence of alcohol on the surfactant micellization. For example, Rao and Ruckenstein [22] and Nishikido et al [13] suggest that short chain alcohol increases the CMC of surfactant, Fig. 1.…”

“…In the literature, it is possible to find many data dealing with the behavior of surfactants and alcohols in the surface monolayer at the solution-air interface formed from aqueous solutions at low alcohol concentrations [10][11][12], but few data dealing with their volumetric and adsorption properties in the wide range of alcohol concentrations [13][14][15]. However, it is difficult to find in the literature the correlation between the volumetric and the adsorption properties of surfactant and alcohol mixtures in the range of their concentrations in which both surfactant and alcohol can be present in solutions in the monomeric and aggregated forms in light of different kinds of intermolecular interactions.…”

Cyclic Voltammetry of Retinol in Surfactant Media and Its Application for the Analysis of Real Samples

“…Methanol is the only alcohol that increases the surfactant CMC [28]. This is caused by highest polarity of methanol in comparison with other alcohols and better solvation of surfactant monomers increasing their solubility in water.…”

Electrophoretic deposition (EPD) of hydrous ruthenium oxides with PTFE and their supercapacitor performances

“…Because free surfactants are stabilized by ethanol molecules, micelles of non-ionic surfactant would be disassembled in the ethanol-water mixture solution, resulting in adsorption of PTFE on hydrous ruthenium oxides ( Fig. 1c [16,17]. Then, by applying voltage gradient (50 V/cm), hydrous ruthenium oxide/PTFE particles with positive zeta-potential (ca.…”