Interactions of Tween 20, 60 and 80 with dye molecules: Spectroscopic analysis

The behaviour of the pyrene (Py), 8-anilino-l-napthalenesulfonic acid ammonium salt (ANS) and Pyronin Y (PyY) in the Tween series of polyoxyethylene nonionic surfactants contained aqueous solutions was investigated using the fluorescence spectroscopic technique. The object of investigations were the interactions between the given dye and the surfactant in a wide range of surfactant concentrations and the temperature range from 293 to 318 K. The obtained spectra were the basis for determination of the critical micelle concentrations (CMC) of the surfactants, thermodynamic analysis of the dye-surfactant binding process and correlation with the micropolarity and microviscosity of the dye environment. The parameters changes with concentration and temperature were also studied from the intermolecular interactions in the solution of a given surfactant. (C) 2019 Elsevier B.V. All rights reserved.