Seminario "Shear-inverted nematic emulsion: the role of defects" (Dr. A. Tiribocchi)

ABSTRACT. Suspensions of particles in a host fluid are a widespread state of matter; they can be solid, such as colloids, or liquid, such as emulsions, and are of remarkable technological importance, with applications ranging from paints and cosmetics to food products.

Of particular relevance are a type of emulsions made up of isotropic droplets dispersed into a liquid crystal (nematic or cholesteric) which lead to the formation of defects in the liquid crystal near the surface of the droplet.

We study, by numerical simulations, the rheology of an emulsion embedded in a nematic host when a shear force is applied and show that dynamics are affected by the position of the defects.

While a Newtonian binary fluid-like behavior dominates when defects are absent (typically for low surface anchoring strength), more complex dynamics are exhibited if defects are near the droplet surface (for higher surface anchoring strength).

They can acquire motion and either display periodic oscillations along the surface of the droplet or migrate away from it dragged by the fluid. Droplet typically deforms along the shear flow, can acquire motion as well and break for high shear rates.

Persona di contatto:Prof. Giuseppe Gonnella

Relatore:Dr. Adriano Tiribocchi (U. di Padova)