Order induces toughness in anisotropic colloidal crystal composites.

Spatial ordering of matter elicits exotic properties sometimes absent from a material's constituents. A few highly mineralized natural materials achieve high toughness through delocalized damage, whereas synthetic particulate composites must trade toughness for mineral content. We test whether ordering the mineral phase in particulate composites through the formation of macroscopic colloidal crystals can trigger the same damage resistance found in natural materials. Our macroscopic silica rod-based anisotropic colloidal crystal composites are processed fully at room temperature and pressure, reach volume fractions of mineral higher than 80%, and aided by a ductile interface, unveil toughness up to two orders of magnitude higher than bulk silica through the collective movement of rods and damage delocalization over millimeter. These composites demonstrate key design rules to break free from conventionally accepted structural materials' properties trade-off.