Physics of interfaces have enjoyed a renewed interest thanks to the introduction of new experimental tools and theoretical concepts able to design and rationalize interfaces with large degree of complexity (surfaces with controlled gaussian curvatures, liquid crystal shells), in which colloidal systems show original dynamics. Thanks to lithography and microfluidics, such complex interfaces are designed. In this context, the main results of the group concern : (1) the design and characterization of liquid interfaces presenting complex morphologies and order and their coupling with colloidal particles trapped on them ; and (2) the characterization of static and dynamic properties of liquid crystal interfaces presenting correlated quenched disorder. We have expertise with manipulations of particles based on optical tweezers or microfluidic approaches. We have also developed original experimental setups based on optical tools (microscopy, optical trappings, scattering, holography and ellipsometry) allow measuring diffusion coefficients, contact angles and interactions between colloids at these interfaces.
Surfoids : Colloids @ fluid interfaces. The interface between two fluids is extremely efficient to trap particles ranging from nanometer to millimeter sizes. In the past, this strong 2D confinement has been used to address fundamental problems of condensed matter physics considering colloids as “big” atoms. Nowadays the interest for these systems is enriched by their large impact for applications and industrial processing. In particular making functional materials by colloidal self-assembly (...)
Liquid crystal emulsions Competition between elasticity and interface tension might also produce complex shapes in liquid crystals emulsions. Using surfactants design and microfluidics techniques, we obtained several original systems such as nematic filaments or smectic shells (see Figure 1 and 2) in water/LC/water double emulsions and explained the underlying mechanisms that control their shape and textures. Topological constraints and liquid crystal elasticity yield fascinating (...)
Disorder and dynamics at liquid crystal/solid interfaces Anisotropic particles, because of their extra orientational degree of freedom, have in general a much richer behavior than spherical ones. They can form liquid crystalline phases at high concentrations. At lower concentrations, their orientation can be controlled by an external field : electric or elastic as in the case of suspensions in a liquid crystal. In a composite, their proper anisotropic properties can be transferred to the (...)