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Path-Dependent Self-Assembly of Magnetic Anisotropic Colloidal Peanuts
Md Arif Kamal1, Andrei V Petukhov2, Antara Pal3
1Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), CNRS, Aix-Marseille University, 13007 Marseille, France.
The Journal of Physical Chemistry. B
|June 10, 2020
Summary
Field-induced self-assembly of peanut-shaped particles creates tunable structures. Applying a magnetic field during or after sedimentation controls the formation of nematic or dipolar chain phases.
Area of Science:
- Colloid and Surface Science
- Materials Science
- Soft Matter Physics
Background:
- Anisotropic colloidal particles offer unique self-assembly possibilities.
- Controlling particle interactions is key to designing advanced materials.
Purpose of the Study:
- To investigate the field-induced self-assembly of anisotropic hematite-silica core-shell particles.
- To explore how the timing of magnetic field application influences self-assembled structures.
Main Methods:
- Utilized small-angle X-ray scattering with microradian resolution (μrad-SAXS).
- Applied external magnetic fields at different stages of particle sedimentation.
Main Results:
- Self-assembled structures depend on the timing of magnetic field application.
- Nematic phases form when the field is applied post-sedimentation; dipolar chains form when applied during sedimentation.
- Observed unusual diffraction peak shapes in dipolar chains, suggesting para-nematic phase formation.
Conclusions:
- The timing of external field application is a critical parameter for controlling colloidal self-assembly.
- Hematite-silica particles exhibit tunable phase behavior, forming oblate nematic and smectic phases despite their prolate shape.
- Dipolar chains act as building blocks for higher-order structures.
