Coupled interfacial phenomena suppress propulsion in catalytic Janus colloids

Area of Science:

• Colloid and Surface Science
• Nanotechnology
• Chemical Engineering

Background:

• Janus particles exhibit complex motion in solutions, crucial for microscale applications.
• Boundary interactions significantly affect Janus particle dynamics.

Purpose of the Study:

• Investigate how cap thickness and hydrogen peroxide concentration influence Janus particle velocity and displacement.
• Understand the role of orientational quenching in particle dynamics near boundaries.

Main Methods:

• Analyzed platinum-coated polystyrene Janus particles with varying cap thicknesses (3-35 nm).
• Studied particle behavior in 1% and 3% hydrogen peroxide solutions near fluid cell boundaries.
• Measured particle velocity and maximum displacement under different conditions.

Main Results:

• Lower cap thicknesses correlated with higher particle velocities.
• Higher hydrogen peroxide concentrations (3%) resulted in faster particle movement.
• Particle boundary preference (ceiling vs. flooring) depended on a combination of activity and gravity, influenced by cap weight and peroxide concentration.
• Plasma cleaning a single surface reduced overall particle velocity.

Conclusions:

• Janus particle dynamics near boundaries are tunable via cap properties and solution chemistry.
• Surface treatment and propulsion force are key factors governing particle behavior.
• Findings inform the design of Janus particles for targeted microscale transport and delivery systems.