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Pt-SiO2 Janus Particles and the Water/Oil Interface: A Competition between Motility and Thermodynamics
Zohreh Jalilvand1, Hamad Haider1, Jingqin Cui2
1Department of Chemical Engineering, The City College of New York, New York , New York 10031, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|February 13, 2020
Summary
Motility engineering in Janus particles (Pt-SiO2) near liquid interfaces was studied. Active Janus particles swim near water/oil interfaces, preventing adsorption, unlike passive particles.
Area of Science:
- Colloid and Surface Science
- Soft Matter Physics
- Nanotechnology
Background:
- Janus particles exhibit unique interfacial behavior.
- Previous studies focused on passive Janus particles near liquid/liquid interfaces.
- The impact of particle motility on interfacial behavior remained unexplored.
Purpose of the Study:
- To investigate the effect of motility on Janus particle behavior at water/oil interfaces.
- To engineer the interfacial activity of Janus particles by introducing self-propulsion.
- To understand the mechanisms governing the orientation and movement of active Janus particles near liquid interfaces.
Main Methods:
- Utilized platinum-capped silica (Pt-SiO2) Janus particles (8 μm).
- Introduced motility via hydrogen peroxide (H2O2) solution, inducing self-propulsion.
- Observed particle behavior near a water/oil interface using experimental techniques.
Main Results:
- Passive Pt-SiO2 Janus particles adsorb to the interface, with Pt-caps facing oil.
- Active Pt-SiO2 Janus particles orient sideways and swim parallel to the interface.
- H2O2 decomposition creates an O2 gradient, enabling hydrodynamic interactions and controlled swimming.
- Motility restricts out-of-plane rotation, preventing interface adsorption.
Conclusions:
- Motility can be engineered in Janus particles to control their interfacial behavior.
- Active Janus particles exhibit distinct swimming dynamics near liquid/liquid interfaces.
- This study opens avenues for designing active interfacial colloids for targeted applications.
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