A model on the temperature dependence of critical micelle concentration

An equation, which describes the dependence of critical micelle concentration (X-CMC) with temperature, has been derived on the basis of DeltaG(0) = -RTln K, linear behavior of the enthalpy of micellization with temperature, and compensation phenomena in which the enthalpy and the entropy of micellization change linearly with each other. The new equation has yielded excellent fitting results of X-CMC(T) for various surfactant systems. More interestingly, it yields d = 2, irrespective of surfactant system, in the power-law description of X-CMC(7), \X-CMC - X*(CMC)\ = const\T-T\(d) with the minimum CMC, X*(CMC), and the temperature, T* at X*(CMC). The value of d = 2 is confirmed from the fits to reported literature data. (C) 2004 Elsevier B.V. All rights reserved.