Superdiffusion of concentration in wormlike-micelle solutions

Abstract

Our dynamic light scattering studies of viscoelastic wormlike-micelle solutions of surfactant cetyltrimethylammonium tosylate (CTAT) show superdiffusive relaxation of concentration fluctuations: relaxation rate similar to q(z) at wavenumber q, with z < 2, at concentrations just past overlap. Linear rheology experiments show that the micellar recombination kinetics in this system is diffusion-controlled ( micelles break and recombine with their original partners). Addition of 10 mM to 100 mM of sodium chloride ( NaCl), takes the system from the diffusion-controlled ( DC) regime to mean-field recombination kinetics regime where micellar ends combine with ends belonging to other micelles. In the mean-field regime, the concentration fluctuations decay in a purely diffusive manner. We suggest a qualitative explanation for the observed superdiffusive behaviour in the DC regime.

Publication
EPL 77, (2007).
Date
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