VULCAN: matter, powered from within

Vulcan, the Roman god of blacksmithing, was revered in Europe since the Iron Age (1200-500 BC) for a powerful skill: controlling the macroscopic properties of metals (strength, ductility, toughness). To this day, thermal treatments such as annealing - cycles of high temperatures, alternated with slow cooling - remain an essential tool of material science. However, Vulcans traditional powers forge monolithic, static, and passive materials, and are laughably blunt instruments when compared to living materials, which dynamically reconfigure, repair, and rebuild themselves. Living systems provide proof-of-concepts for what can be achieved: assembling functional materials from elementary blocks that consume fuel. VULCAN: matter, powered from within, takes forging into the modern age, injecting energy directly through active agents present in the materials. It is experiment-driven and bottom-up, establishing novel experimental strategies to fabricate materials powered from within, with phases and structures that cannot be achieved via thermal treatments, and present non-conventional mechanical and rheological properties (self-healing, odd viscosities). The proposal notably aims to control the phase diagram of matter with spatiotemporal modulation of activity of the bath. We will devise an active bath of swimming bacteria to assemble macroscopic and 3D colloidal crystals and gels [Objective 1], with structures and at scales that cannot be achieved thermally. In parallel, we will devise exotic condensed phases of matter: 2D liquids of spinners and networks of active beams [Objective 2], made from large numbers of autonomous micromachines built from light-activated colloids. This is uncharted territory and an ambitious and high-risk goal, fueling VULCANs lasting impact tearing down the boundary between Active Matter and Materials Science - and opening the path to a new class of materials, powered from within, with applications in (bio)engineering and photonics.