Thermodiffusion of Charged Micelles

Abstract

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/S(T) is a linear function of the colloid density n; the proportionality factor, or second virial coefficient, varies algebraically with inverse salinity, n0(-alpha); the precise value of the exponent alpha 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.

Single-particle thermal diffusion of charged colloids: Double-layer theory in a temperature gradient

“…[2] and in refs. [4,5] is quite satisfactory, since the approaches are rather different. In addition to the single-particle Soret coefficient, ref.…”

“…when d ln Q/d ln T = 0). Bringuier and Bourdon [4] and Fayolle et al [5] propose an expression for the single particle thermal diffusion coefficient in terms of the temperature derivative of the total internal energy, based on arguments within a statistical mechanics approach that is put forward by van Kampen [6].…”

Experimental Determination of the Soret Coefficient of Ionic Ferrofluids: Influence of the Volume Fraction and Ionic Strength

“…Following Ref. [5,14,15], the Soret coefficient S T is proportional to the osmotic compressibility χ T (Φ) of the dispersion and writes:…”

Study of the thermal diffusion behavior of simple binary mixtures

“…The present equations of state require modification for the precise calculation of the Soret coefficient. At the same time, the theoretical concepts developed for colloidal dispersions [171,115,106,150,50] show a better agreement with experiments. A detailed overview can be found in PhD thesis by Ning [105].…”

“…Equilibrium simulations we performed at constant pressure and temperature using the Berendsen's thermostat [16] dT dt 50) where P and T are the actual temperature and pressure of the system, P bath and T bath are the target values, τ P and τ T are characteristic times which determine how quickly the system reacts to a deviation from the target values. A constant temperature is regulated by a uniform scaling of the atom velocities and a constant pressure by a uniform scaling of the atom positions and the box lengths.…”