El Dr. Marcel Rey (University of Gothenburg, Suecia) expondrá el seminario titulado «Stimuli-responsive emulsions & Overcoming the coffee ring effect».
Resumen: In this seminar, I will talk about our recent advances on understanding the behaviour of stimuli-responsive emulsions and afterwards I will introduce a simple yet versatile strategy to overcome the coffee ring effect and obtain homogeneous drying of particle dispersions.
Temperature-responsive emulsions combine the long-term stability with controlled on-demand release of the encapsulated liquid. The destabilization has previously been attributed to microgel shrinkage, leading to a lower surface coverage which induces coalescence [1,2].
During my post-doc in Edinburgh, we demonstrated that breaking mechanism is fundamentally different than previously thought. Breaking only occurs if the stabilizing soft microgel particles assume a characteristic double-corona microstructure, which serve as weak link enabling stimuli-responsive emulsion behavior. Conversely, emulsions stabilized by regular single-corona microgels remain remarkably insensitive to temperature.[3]
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. [4]
- Fecha: Jueves 1 de diciembre de 2022
- Lugar: Facultad de Ciencias – Aula A22.
- Horario: de 12:00 a 13:00 h.
- Organiza: Grupo de Física de Fluidos y Biocoloides
- Más información:
Miguel Ángel Fernández Rodríguez
Correo: mafernandez@ugr.es
Departamento de Física Aplicada