Thermodiffusion of charged micelles
Résumé
We study diffusion of charged nanoparticles in a temperature gradient and derive the corresponding Ludwig-Soret transport coefficient. Charge effects are found to enhance thermodiffusion by up to 2 orders of magnitude. We show that the inverse Soret coefficient 1/ST is a linear function of the colloid density n; the proportionality factor, or second virial coefficient, varies algebraically with inverse salinity, n0-α; the precise value of the exponent α depends on the ratio of particle size and Debye length. Our findings compare favorably with experimental observations and provide, without adjustable parameters, a good fit to the data on 3-nm sodium dodecylsulfate micelles.