Colloids present a rich landscape of nano-objects, varying in shape and density, which provide numerous opportunities for adjusting the rheological properties of colloidal suspensions. They can be classified according to their form factor and their softness. Colloid can be isotropic, such as silica particles (hard spheres), or anisotropic, such as cellulose nanofibers. The versatility of polymer architectures gives access to soft colloids presenting different levels of elasticity and inter-penetrability, such as microgels, star polymers and core-shell particles. Although the suspension behaviour of model single-shaped colloids has been widely reported, colloidal mixtures remain virtually unexplored. Previous works in our team has produced a variety of soft and hard
isotropic binary colloidal systems with tuneable interactions based on supramolecular bonds. The objectives of this experimental PhD project are to design mixtures of isotropic and anisotropic bio-based colloids, to investigate widely their behaviour in terms of phase diagram, rheological and structural properties. This model bio-based binary systems will be formulated from chitosan microgels (isotropic colloids) and chitin nanofibers (anisotropic colloids). Fundamental aspects will be addressed regarding the influence of isotropic/anisotropic ratio on the liquid-solid transition, the accessible organized phases and birefringence properties. Those properties are crucial for innumerable applications.
