Soft Solids and Sustainable Materials

From toothpaste to glass, cement, compacted sand, and even yogurt or chocolate mousse,  soft amorphous solids have disordered structures and often exist at the margin of mechanical stability.

We  use computational statistical physics to build connections and feedbacks with experimental observations and new theories in this fascinating area of  physics.

Gel Mechanics

Gel networks are ubiquitous in nature, with their highly adaptive and tunable rheological response being central to their function in biology as well as engineering. They can be stretched, flow, squeezed or fractured, but a fundamental understanding of such processes is still lacking. We are investigating how the topology of the gel network can determine softening, strain-hardening and brittleness, and how different structural constituents and frozen-in stresses can modify the gel mechanics.

Yielding and failure of jammed soft materials

Soft jammed materials, from compressed emulsions to cell monolayers, yield under deformation and eventually flow through avalanches of localized plastic rearrangements. We develop spatio-temporal analysis of the microscopic dynamics  to investigate the rate dependent yielding and flow,  the emergence and the persistence of flow inhomogeneities,  the failure under tension.

Cement cohesion and mechanics

Cement is the main binding agent in concrete and the second most consumed substance in the world behind water, in spite of its environmental footprint (5-8% of the whole man-made COcomes from cement production). Greener cements can be a game changer for a more sustainable infrastructural and urban growth at this point. We have developed the first quantitative model and computational approach for gelation and densification of cement hydrate gels that form in early stages of cement hydration and are crucial to mechanics and hygro-thermal behavior of cement and concrete. Our research has reconciled contrasting experimental findings and set the path to pursue scientifically guided optimization of cement properties, opening new possibilities for effective novel formulations of green cements.

Dynamical heterogeneities in gels and glasses

Cooperative dynamics that emerge during solidification and aging of soft materials are crucial to their mechanical behavior. We have devised a novel spatio-temporal analysis of such cooperative and heterogeneous dynamics to elucidate the role of soft modes, structural heterogeneities and topology. In a recent study we have discovered the fundamental mechanism governing spatio-temporal correlations and fluctuations in soft solids and at the origin of their aging dynamics, with materials of interest ranging from biopolymer networks to microgels, protein gels and even metallic glasses. We have shown that, due to large stress heterogeneities frozen-in during solidification, microscopic ruptures and rearrangements underlying the aging are dominated by the elasticity stored in the material structure, which produces intermittent and strongly correlated dynamics.

Nano-patterned interfaces and adsorption processes

The adsorption of nano- and micro- objects at liquid and solid interfaces is a major strategy for creating novel composites. We want to unravel the role of the adsorption kinetics and interfacial jamming in range of systems spanning from polymer coated nanoparticles at liquid interfaces, to proteins and protein fibers on solid substrates. We have demonstrated that the adsorption kinetics can be tuned, through the physical-chemistry of the system, to design specific structural defects (and dynamical processes) and hence used to modify the characteristics of the patterned interfaces.