Probing sedimentation non-ideality of particulate systems using analytical centrifugation

Area of Science:

• Colloid and Surface Science
• Materials Science
• Physical Chemistry

Background:

• Analytical centrifugation precisely characterizes colloidal systems, determining particle size, shape, and density.
• Recent advancements enable accurate analysis of particle interactions and concentration-dependent sedimentation coefficients.
• Understanding sedimentation non-ideality is crucial for predicting colloidal system behavior.

Purpose of the Study:

• To develop a holistic approach for quantifying sedimentation non-ideality in silica nanoparticles using analytical centrifugation.
• To investigate the influence of particle size, polydispersity, and electrostatic interactions on sedimentation properties.
• To correlate experimental findings with simulations for a comprehensive understanding of colloidal behavior.

Main Methods:

• Utilized high-precision analytical centrifugation for quantitative characterization of silica particles (100-1200 nm).
• Employed lattice Boltzmann and Brownian dynamics simulations to model particle interactions and polydispersity effects.
• Conducted conductivity measurements to determine the repulsion range (Debye length/interparticle distance).

Main Results:

• Demonstrated accurate quantification of sedimentation non-ideality for polydisperse silica nanoparticles.
• Showcased the impact of electrostatic interactions, quantified by repulsion range, on sedimentation behavior.
• Validated simulation predictions with experimental data for both neutral hard spheres and charge-stabilized systems.

Conclusions:

• Analytical centrifugation is a powerful tool for quantifying sedimentation non-ideality in diverse colloidal systems.
• Both hard-sphere interactions and electrostatic forces significantly influence concentration-dependent sedimentation properties.
• The developed approach enables detailed characterization of particulate systems, even with moderate heterogeneity and complex interactions.