The self-aggregation of Tween 40, Tween 60, and Tween 80 in ethylene glycol-water mixture was investigated using surface tension, density, and fluorescence measurements. The mixtures were observed to appreciably affect the critical micelle concentration (cmc) of the surfactants and their aggregation numbers. In order to evaluate the influence of the solvent mixture, the difference in the Gibbs energy of micellization of Tween 40, Tween 60, and Tween 80 between water and binary mixtures were determined. The ability of ethylene glycol acting as a structure breaker and its interaction with the surfactant hydrophilic group are the controlling factors for the micellization of the surfactants in the mixture. The surface activity of the surfactants decreases with increasing concentration of ethylene glycol in the mixture. Micellar micropolarity was determined using the fluorescence method. The results indicate the participation by ethylene glycol in the micellar solvation layer.

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