This is part of a seminar series for students and researchers interested in theoretical physics and applied mathematics. Listen to Marcel Rey(University of Gothenburg) uring the seminar "Soft Matter and its Interactions".
Abstract: Soft materials encompass an intriguing class of substances, ranging from suspensions and gels to foams and emulsions. These materials are often constructed from discreet building blocks such as molecular, polymeric, or colloidal entities. Understanding the interactions and properties of these building blocks is key to develop new classes of soft materials.
In this talk, I will first introduce how isotropic building blocks can form anisotropic structures. Then, I will introduce a simple trick 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. [1] 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. [2]
[1] Rey M, Law A, Buzza M, Vogel N. Journal of the American Chemical Society, 2017
[2] Rey M., Walter J., Harrer J., Morcillo Perez C., Chiera S., Nair S., Ickler M., Fuchs A., Michaud M., Uttinger M.J., Schofield A.B., Thijssen J.H.J., Distaso M., Peukert W. & Vogel N. Nature Communications, 2022
Participate on campus or via Zoom.
On campus: PJ lecture hall and via Zoom
Zoom link: https://gu-se.zoom.us/j/64681043702