Interfacial colloidal rod dynamics: Coefficients, simulations, and analysis.

Area of Science:

• Colloid and Interface Science
• Soft Matter Physics
• Computational Fluid Dynamics

Background:

• Understanding colloidal rod diffusion is crucial for applications in materials science and nanotechnology.
• Existing models often simplify rod hydrodynamics, neglecting key interactions near interfaces.
• Accurate diffusion tensors are needed for predicting particle behavior in complex environments.

Purpose of the Study:

• To develop and validate a constrained Stokesian dynamics model for colloidal rod diffusion near a wall.
• To compute complete diffusion tensors, including hydrodynamic interactions and translation-rotation coupling.
• To provide theoretical tools for interpreting experimental data on colloidal rod diffusion.

Main Methods:

• Modeling colloidal rods as chains-of-spheres.
• Computing complete diffusion tensors in bulk and near interfaces.
• Simulating particle trajectories using the derived diffusion tensor.
• Quantifying diffusion using mean squared displacements and autocorrelation functions.

Main Results:

• Complete diffusion tensors were computed for colloidal rods, accounting for hydrodynamic interactions and translation-rotation coupling.
• Simulated trajectories accurately reflect experimental quantities like mean squared displacements.
• Theoretical expressions predict average diffusivities and the transition from anisotropic to isotropic diffusion.

Conclusions:

• The chains-of-spheres model accurately captures colloidal rod diffusion near walls.
• The computed diffusion tensors and theoretical expressions aid in interpreting and predicting experimental results.
• This work provides a valuable framework for studying colloidal rod behavior in interfacial and confined systems.