Marcel Rey
Presentation for the School of Materials at the University of Manchester
Date: 20 July 2023
In this seminar, I will talk about complex self-assembly behaviour of simple building blocks. Afterwards, I will introduce a simple yet versatile strategy to overcome the coffee ring effect and obtain homogeneous drying of particle dispersions.
Spherical colloidal particles confined at liquid interfaces typically self-assemble into hexagonal packing. Here, I will show that much more complex self-assembly behaviour is possible spherical particles with a hard-core / soft-shell architecture. Upon compression, these core-shell particles transition from a hexagonal packing to a chain packing, then to a square packing and finally to a hexagonal close packing. I will rationalize these experimental observations with calculations and simulations using simple core-shell potentials.
After spilling coffee, a tell-tale circular stain is left by the drying droplet. This universal phenomenon, known as the “coffee ring effect”, is observed independent of the suspended material. We recently developed a simple yet versatile strategy to achieve homogeneous drying of dispersed particles. Modifying the particle surface with surface-active polymers provides enhanced steric stabilization and facilitates adsorption to the liquid/air interface which, after drying, leads to uniform particle deposition. This method is independent of particle size and shape and applicable to a variety of commercial pigment particles promising applications in daily life.