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Superparamagnetic colloids in a rotating field: Transition state from chains to disks
F Mignolet1, A Darras1, G Lumay1
1GRASP Laboratory, CESAM Reasearch Unit, University of Liège, B-4000 Liège, Belgium.
Physical Review. E
|October 21, 2022
Summary
Superparamagnetic colloids form rotating chains and disklike clusters under magnetic fields. This study models the aggregation dynamics, observing chains transform into clusters over time.
Area of Science:
- Colloid science
- Soft matter physics
- Magnetism
Background:
- Superparamagnetic colloids self-organize into structures under external magnetic fields.
- Field characteristics dictate the resulting colloidal arrangements, such as chains or clusters.
Purpose of the Study:
- To investigate the early aggregation stages and dynamics of disklike cluster formation in superparamagnetic colloids.
- To model the temporal evolution of colloidal structures under rotating magnetic fields.
Main Methods:
- Experimental observation of colloidal behavior under controlled magnetic fields.
- Development of a mathematical model to quantify structural proportions over time.
Main Results:
- Colloids initially form rotating chains, which then interact and aggregate into disklike clusters.
- A mixture of chains and disklike clusters is observed as aggregation progresses.
- The model successfully characterizes the suspension's evolution based on frequency and volume fraction.
Conclusions:
- The transition from rotating chains to disklike clusters is a key dynamic in this system.
- The proposed model provides a quantitative framework for understanding these aggregation processes.
- Findings are relevant for controlling self-assembly in magnetic colloidal suspensions.
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