Diffusiophoresis of Macromolecules within the Framework of Multicomponent Diffusion.

Area of Science:

• Colloid and Interface Science
• Physical Chemistry
• Transport Phenomena

Background:

• Diffusiophoresis describes isothermal particle migration driven by solute concentration gradients.
• Traditionally explained via hydrodynamics, it can also be framed within multicomponent diffusion theory.
• Understanding diffusiophoresis is crucial for controlling particle behavior in complex fluids.

Purpose of the Study:

• To review the connection between diffusiophoresis and the diffusion-coefficient matrix of ternary liquid mixtures.
• To explore the theoretical interpretation of diffusiophoresis using fundamental thermodynamic and transport parameters.
• To examine experimental data and underlying mechanisms of diffusiophoresis and osmotic diffusion.

Main Methods:

• Utilizing the framework of multicomponent diffusion to analyze diffusiophoresis.
• Extracting diffusiophoresis and osmotic diffusion coefficients from measured ternary diffusion coefficients.
• Employing precision Rayleigh interferometry at 25 °C for ternary diffusion measurements.
• Examining preferential-hydration and electrophoretic mechanisms.

Main Results:

• Diffusiophoresis is directly linked to a cross-term diffusion coefficient in ternary mixtures.
• Osmotic diffusion describes cosolute movement driven by particle concentration gradients.
• Experimental data for polyethylene glycol and lysozyme demonstrate these phenomena.

Conclusions:

• Multicomponent diffusion provides a robust framework for understanding diffusiophoresis and osmotic diffusion.
• The study connects these phenomena to preferential-interaction coefficients, Onsager relations, and Nernst-Planck equations.
• This approach facilitates theoretical interpretation and experimental analysis of particle transport in solutions.