Interparticle friction in colloidal materials

Colloidal materials, soft matter built from micrometric particles in a fluid, are ubiquitous in nature and the synthetic realm (e.g., foods, gels, and paints). To date, the role of friction in these flowing and deformable materials remains surprisingly poorly understood at the microscopic level. My research employs microscopy and computer simulations to explore, at the level of individual building blocks, how friction between particles affects the material properties. In my experiments, I use unique colloidal particles characterized by a uniform composition and a non-uniform fluorescence profile (see inset), allowing for the simultaneous tracking of centroid positions and orientations of all spheres in three dimensions. This unique feature enables a quantitative investigation of rolling constraints between individual particles resulting from frictional interactions. My project aims to establish fundamental insights into the emergence and tunability of microscopic frictional interactions. This, in turn, opens up a novel avenue for tailoring the macroscopic bulk behavior of colloidal materials.