Dynamic adhesion behavior of micrometer-scale particles flowing over patchy surfaces with nanoscale electrostatic...

Area of Science:

• Colloidal science
• Surface science
• Fluid dynamics

Background:

• Understanding particle adhesion is crucial in various fields, including microfluidics and materials science.
• Electrostatic interactions and surface heterogeneity significantly influence particle-wall dynamics.

Purpose of the Study:

• To numerically investigate the dynamic adhesion behavior of micrometer-scale silica particles on a heterogeneous surface under shear flow.
• To explore the role of electrostatic interactions and surface charge distribution in dictating particle adhesion mechanisms.

Main Methods:

• Numerical simulation of low Reynolds number shear flow.
• Coupling hydrodynamic forces with spatially varying colloidal interactions.
• Inclusion of contact and frictional forces to model particle skipping, rolling, and arrest.

Main Results:

• Particle behavior transitions from no contact to skipping, rolling, and arrest with increasing cationic patch density (Theta).
• A critical patch density (Theta(crit)) is required for adhesion, showing quantitative agreement with experiments.
• Ionic strength tunes adhesion by modulating electrostatic interaction range and strength, influencing particle-wall attraction and arrest.

Conclusions:

• Surface electrostatic heterogeneity provides a mechanism to control dynamic particle adhesion.
• Adhesion regime diagrams illustrate selective adhesion based on particle size and surface properties.
• Findings suggest novel strategies for controlling particle-wall interactions using engineered surface heterogeneity.