Abstract
This work brings together two strands of research on the behaviour of colloidal dipolar matter. The first part is a simulation-based study of the minimum energy clusters of Lennard-Jones particles with induced dipoles. The second part of this work is an experimental study of the phase behaviour of active metallodielectric Janus colloids in three dimensions.First, we present a study of the cluster behaviour of dipolar particles. The minimum energy clusters of particles with induced dipoles and isotropic Lennard-Jones interactions are identified using the GMIN optimisation tool. It is shown that the interplay between the isotropic and dipolar interaction produces several types of distinct clusters as the dipole strength is increased. These include polytetrahedra, Bernal spirals and octahedra. These clusters are then implemented into the "Topological cluster classification". This is a topological tool that identifies target structures, with the aim of identifying short-range structures in fluids.
Finally, Brownian dynamics simulations of dipolar particles are performed, and the populations of the target clusters are calculated.
The second part of this work is an experimental study of active metallodielectric Janus particles in three dimensions. The interplay between active and dipolar forces in an applied electric field is found to be tunable by changing the frequency of the applied field. We identify an active percolating labyrinth, active crystallites, active string fluid, active fluid and an active glass. Metallodielectric Janus colloids are made active by a metal cap on one hemisphere of the particle.
In the final part of this investigation, we present a study of the effect of metal cap thickness and volume fraction on the phase behaviour.
| Date of Award | 23 Jan 2024 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Adrian C Barnes (Supervisor) & Paul Bartlett (Supervisor) |
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