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Fourier Transform Near-Infrared Examination of the Coagel-to-Micelle Transition for Sodium Laurate

Volume 46, Number 4 (April 1992) Page 701-704

Cross, W.M.; Kellar, J.J.; Miller, J.D.


The solution behavior of surfactants has received considerable attention, because it is known that, for certain equilibrium conditions of concentration, temperature, and pressure, surfactant molecules form stable aggregates in solution. The ability of surfactants to aggregate in aqueous solutions and at solid/liquid interfaces has been shown to be important in many areas of science, including biology, detergency, and mineral flotation. Over the past ten years, infrared radiation has been used to spectroscopically examine thermotropic and lyotropic phase transitions for various surfactant systems such as sodium alkanoates, phospholipids, and sodium alkylsulfates. The results of these studies indicated that many phase changes, especially monomermicelle and coagel-micelle transitions, are accompanied by large (4-8 cm−1) shifts in the fundamental frequencies of the asymmetric and symmetric alkyl stretching bands. These shifts have been attributed to differences in the number of gauche rotational isomers in the alkyl chain of the surfactant studied.