Ho-Kei Chan - Confinement-induced columnar crystals: A route to new architecture in the scientific world
| Dates: | 5 May 2021 |
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| Times: | 14:00 - 15:00 |
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| What is it: | Seminar |
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| Organiser: | Department of Mathematics |
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| Who is it for: | University staff, External researchers, Current University students |
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Ho-Kei Chan (Harbin Institute of Technology) joins us for this virtual seminar in the Physical Applied Mathematics Series
This seminar will be held via Zoom. Please email chris.johnson@manchester.ac.uk if you require the meeting details.
Identical spheres in cylindrical confinement exhibit a complex variety of densest-packed columnar structures. Such densest-packed structures can serve as theoretical models for the structures of a variety of quasi-one-dimensional physical systems, such as nanotube-confined fullerenes, nanochannel-confined copolymers, colloidal crystal wires, capillary-tube-confined thermoresponsive microspheres, capillary-tube-confined microbubbles, and fluid-driven self-assemblies of polymer beads. On the other hand, there have been comparatively few studies of this kind for shape-anisotropic particles. Thanks to their rotational degrees of freedom, shape-anisotropic particles in cylindrical confinement exhibit densest-packed structures with non-trivial orientational order, and therefore they demonstrate a greater variety of densest-packed crystal structures than their spherical counterparts.
In this talk, I will present a historical overview of research on the densest-packed structures of identical hard spheres in cylindrical confinement, and then present our recent extensions of such research to shape-anisotropic particles. For packings of spheres, I will introduce a variety of columnar crystals as discovered computationally in the past two decades, and explain how a wide range of such structures can be obtained through a method of sequential deposition. I will also discuss how some ordered but non-densest crystal structures can be discovered through this specific method of sequential deposition. For packings of shape-anisotropic particles, I will present a variety of densest-packed columnar crystals as discovered recently for identical spheroids in cylindrical confinement and for identical ellipses within a parallel strip. For the case of spheroids, I will explain how the corresponding densest-packed structures arise from a competition between confinement-induced chiral ordering and shape-anisotropy-induced orientational ordering. For the case of ellipses, I will explain why the corresponding densest-packed structures are all affine transformations of particular densest-packed structures of circular disks. It is believed that the confinement-induced crystal structures presented in this talk would constitute a basis for the development of novel low-dimensional materials with tailored translational or orientational order.
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