Pressure-imposed flows of model granular suspensions: from physico-chemistry to mechanics – PEGASUS

The PEGASUS project combines the expertise of the SIMM laboratory (ESPCI) and the MSC laboratory (Université Paris Cité) in soft matter physicochemistry, microtribology, interfacial hydrodynamics, and rheology. The goal is to advance towards a theoretical description of dense granular suspension flows, thereby improving our understanding of these industrially relevant materials (concrete) and to innovative 3D printing applications. Specifically, we aim to:
1. Synthesize large quantities of polymeric particles responsive to physicochemical stimuli, dispersible in water, spanning sizes from tens to several hundred microns.
2. Characterize the surface properties of these particles and quantify their microscopic frictional and adhesive interactions using atomic force microscopy (AFM) in liquid environments.
3. Develop a pressure-imposed rheology cell adaptable to a commercial rheometer, enabling the characterization of the macroscopic frictional rheology of suspensions. By relying on interparticle contact interactions, this macroscopic rheology can be directly related to microscopic properties. We will focus particularly on frictionless suspensions, adhesive regimes, and mixtures of frictional and frictionless particles.
4. Investigate thin-film suspension flows—another category of pressure-imposed flows significantly influenced by interparticle interactions. We will study the formation of suspension piles upon droplet deposition, far from the volume fraction at viscosity divergence, and explore the spreading behaviour of suspensions containing mixtures of frictional and frictionless particles.