Polycatenated Architected Materials

Architected materials derive their properties from the geometric arrangement of their internal structural elements, rather than solely from their chemical composition. They can display remarkable behaviors such as high strength while being lightweight, negative Poisson’s ratios, and shear-normal coupling. However, architected materials so far have either exhibited solid-like or fluid-like behavior, but not both. Here, we introduce a class of materials that consist of linked particles assembled in three-dimensional domains, forming polycatenated architected materials (PAMs). We propose a general framework for PAMs that translates arbitrary crystalline networks into particles’ concatenations and design particles’ geometry. The resulting materials are cohesive, yet the individual particles retain some kinematic freedom. In response to small external loads, PAMs behave like non-Newtonian fluids, showing both shear-thinning and shear-thickening responses. At larger strains, PAMs behave like solids, showing a nonlinear stress-strain relation, like lattices and foams. These responses are regulated by a jamming transition determined by the particles’ arrangement and the direction of loading. PAMs are scalable, showing comparable mechanical responses at both millimeter- and micrometer-scales. However, micro-PAMs can change shape in response to electrostatic charges. PAM’s properties are relevant for developing stimuli-responsive materials, energy-absorbing systems and morphing architectures.