Electric birefringence and elastic and quasi-elastic light scattering investigation of the critical behavior of Triton X-100 in aqueous solution

Abstract

Aqueous solutions of Triton X-100 have been investigated by means of elastic and quasi-elastic light scattering, viscosity, and electric birefringence in the temperature range between room temperature and critical temperature T _c . The intensity of scattered light and the correlation length ξ have been found to follow power laws of (T_c−T)/T_c with exponents equal to those predicted by the renormalisation group theory. Nevertheless some deviations from the Kawasaki-Ferrell universal plot are noted when the correlation range increases much, close to T _c . The decay and the rise of the electric birefringence show the presence of two relaxation processes. The fast relaxation process has been attributed to the individual micelles and its analysis has yielded information on the shape and dimension of the Triton X-100 micelles. The slow process which becomes predominant close to T _c appears to be due to the micelles clusters, present at these temperature. It yields values of the correlation range in good agreement with those obtained from light scattering. The results show that the micelles are anisodiametric and that fluctuations of micelle concentration are anisotropic.