Lightweight, ultra-tough, 3D-architected hybrid carbon microlattices

•Over 100× strength and 2× ductility increases in a 3D-printed photopolymer microlattice •Light yet strong hybrid carbon lattices can withstand ∼50% strain without fracture •A simple way to make robust biocompatible carbon composites of any shape and architecture A lightweight material with simultaneous high strength and ductility can be dubbed the “Holy Grail” of structural materials, but these properties are generally mutually exclusive. Thus far, pyrolytic carbon micro/nanolattices are a premium solution for ultra-high strength at low densities, but intrinsic brittleness and low toughness limits their structural applications. Here, we break the perception of pyrolyzed materials by demonstrating a low-cost, facile pyrolysis process, i.e., partial carbonization, to drastically enhance both the strength and ductility of a three-dimensional (3D)-printed brittle photopolymer microlattice simultaneously, resulting in ultra-high specific energy absorption of up to 60 J g−1 (>100 times higher than the original) without fracture at strains above 50%. Furthermore, the partially carbonized microlattice shows improved biocompatibility over its pure polymer counterpart, potentially unlocking its biomedical and multifunctional applications. This method would allow a new class of hybrid carbon mechanical metamaterials with lightweight, high toughness, and virtually any geometry. A lightweight material with simultaneous high strength and ductility can be dubbed the “Holy Grail” of structural materials, but these properties are generally mutually exclusive. Thus far, pyrolytic carbon micro/nanolattices are a premium solution for ultra-high strength at low densities, but intrinsic brittleness and low toughness limits their structural applications. Here, we break the perception of pyrolyzed materials by demonstrating a low-cost, facile pyrolysis process, i.e., partial carbonization, to drastically enhance both the strength and ductility of a three-dimensional (3D)-printed brittle photopolymer microlattice simultaneously, resulting in ultra-high specific energy absorption of up to 60 J g−1 (>100 times higher than the original) without fracture at strains above 50%. Furthermore, the partially carbonized microlattice shows improved biocompatibility over its pure polymer counterpart, potentially unlocking its biomedical and multifunctional applications. This method would allow a new class of hybrid carbon mechanical metamaterials with lightweight, high toughness, and virtually any geometry.