A Thermodynamic Study on Micellization of Nonionic Surfactant in Water and in Water–Ethanol Mixture by Gel Filtration

Abstract

Micellization of hexa(oxyethylene) dodecyl ether (C12E6) was studied in water and in ethanol–water mixtures at different temperatures by gel filtration on Sphacryl S-200. Standard enthalpies and entropies of micellization were determined from variation of critical micelle concentration(cmc) with temperature. Compensation plots were obtained, slopes for alcohol–water mixtures being indentical with that for pure water. Therefore, the micelle formation in water and ethanol–water mixtures has been explained in terms of its bulk structure. Gel fitration of C12E6 micelle with addition of a large amount of ethanol has led to a finding that the micelle size gradually becomes small with increasing ethanol content until micelles disappear above 35%v/v.

Micelle formation of polyoxyethylene-type nonionic surfactants in bmimBF4 studied by 1H NMR and dynamic light-scattering

“…This phenomenon is known as enthalpy-entropy compensation. The micelle formation process in surfactant solution also exhibits such a compensation phenomenon [25][26][27][28]. It is of interest to examine the relation between enthalpy and entropy for micelle formation in ionic liquids.…”

Enthalpy–Entropy Compensation Phenomenon Observed for Different Surfactants in Aqueous Solution

“…The compensation phenomenon was observed even for the micellization of ionic surfactants in water (5), of a nonionic surfactant in water and in water-ethanol mixture (4), and of ionic surfactants in polar nonaqueous solvents (6). Above all, in 1974, Kresheck and Hargraves determined the changes in enthalpy, entropy, and heat capacity that accompany micelle formation for three Na salts of alkyl sulfates, two dimethylalkylphosphine oxides, and two dodecylpyridinium halides etc.…”

The use of optically active O-alkyl ester hydrochlorides of L-phenylalanine and L-tyrosine as chiral micellar media for the catalysis of diels-alder reactions

“…The optimum yield was obtained when the reaction was carried at 20 o C (Table 1, o C resulted in a change in the micellar structure of the catalyst which reduces the yield of the product and favoring at the same time the formation of the kinetic endo product [25].…”