Sciences et Ingénierie de la Matière Molle-Physico-chimie des Polymères et des Milieux Dispersés

UMR 7615

Self-assembly and aggregation of soft condensed matter like proteins, colloids or polymers into poorly connected and weakly elastic solids is very common and ubiquitous in nature. Phase separation, spinodal decomposition as well as externally driven self-assembly or aggregation often lead to gels, which display diverse structures and solid-like mechanical features. The structural complexity of soft gels entails a versatile mechanical response that allows for large deformations, controlled elastic recovery and toughness in the same material. A limit to exploiting the potential of such materials is the insufficient fundamental understanding of the microstructural origin of the bulk mechanical properties. Investigating how the mechanical response depend on the material microstructure will provide a new rationale, which would ultimately lead to several applications, ranging from improving the performance of batteries (colloidal gels), designing smart composites that can prevent the cascade of catastrophic events and can be used in anti-seismic buildings, and many with important biological function, such as new scaffolds for tissue engineering.
In the first part of my talk, I will present a new highly efficient technique to probe the linear mechanical response of soft gels, as well as a minimal constitutive model. Then I’ll focus on the link between the topology of the network and the non-linear rheological response. I will show the relevance of our analysis to understand the mechanics of F-actin cytoskeleton under large deformations. Our study helps to clarify, the mechanism by which mutations cause podocyte dysfunction and progressive kidney disease in humans. Finally, I will present a new mechanism to account for the non-linear elasticity of a very sparsely connected gels : branched actin networks.