Reversible Adsorption Kinetics of Near Surface Dimer Colloids

Area of Science:

• Colloid and Surface Science
• Physical Chemistry
• Materials Science

Background:

• Understanding particle adsorption kinetics is crucial for applications in materials science and nanotechnology.
• The influence of particle shape on adsorption dynamics is not fully understood.
• Colloidal systems offer a tunable platform to study fundamental interactions.

Purpose of the Study:

• To investigate the effect of particle shape, specifically colloidal dimers versus monomers, on reversible adsorption kinetics.
• To quantify differences in adsorption equilibria and kinetics between dimers and monomers.
• To analyze how different surface coverage definitions impact observed adsorption behavior.

Main Methods:

• Utilized colloidal polystyrene dimers and monomers near a glass surface as a model system.
• Tuned colloid-wall interactions using electrostatic, depletion, and gravity forces to create a double-well potential.
• Measured particle dwell times from trajectories and monomer height via in-line holographic microscopy (<20 nm resolution).

Main Results:

• Dimers with single coverage showed slower adsorption, lower surface coverage, and higher mass coverage than monomers.
• Dimers with double coverage adsorbed faster and achieved higher surface coverage compared to monomers.
• Differences in adsorption were analyzed considering both mass and surface coverage, with two definitions of surface coverage explored.

Conclusions:

• Particle shape significantly impacts reversible adsorption kinetics and equilibria.
• The specific configuration of dimers (single vs. double coverage) dictates their adsorption behavior.
• These findings provide insights into controlling particle assembly and surface functionalization based on shape-dependent adsorption.