Researchers at Caltech have developed a new material that blends the properties of solids and liquids. This material, called polycatenated architected materials (PAMs), offers promising applications in fields like protective gear, biomedical devices, and robotics. The research team, led by Professor Chiara Daraio, created PAMs that change behavior under different stresses.
PAMs consist of complex, interconnected shapes arranged in three-dimensional patterns. These unique structures are produced using 3D printing. Wenjie Zhou, a postdoctoral researcher in Daraio’s lab, spent two years developing these materials.
Initially aiming to create such structures on a molecular scale, Zhou turned to studying PAMs at larger scales to understand their behaviors better. The researchers used various materials like acrylic polymers, nylon, and metals to create 3D-printed PAM prototypes. By subjecting these models to different types of physical stress, they observed that PAMs behaved like liquids when subjected to shear stresses and like solids when compressed.
Polycatentated materials for soft robotics
Daraio explains that PAMs defy traditional classifications of solid and granular materials. Acting as both, these materials flow and change positions like sand while maintaining interconnected structures.
This unique combination offers a range of new properties and applications. Potential applications include helmets, cushioning, biomedical devices, and soft robotics. Co-author Liuchi Li from Princeton University notes that integrating artificial intelligence could further accelerate the exploration of PAMs.
“We started with compression, making the objects harder each time. Then we tried simple shear tests, and finally, we observed how the materials responded to twisting,” said Zhou. He noted that under shear stress, PAMs behave like water with “zero resistance,” while under compression, they become rigid and solid-like.
This research on PAMs represents a fascinating frontier that could redefine material classifications and properties in science and engineering. The study, titled “3D polycatenated architected materials,” was published on January 16, 2025, and was funded by various organizations including the Army Research Office and the US Department of Energy.
Cameron is a highly regarded contributor in the rapidly evolving fields of artificial intelligence (AI) and machine learning. His articles delve into the theoretical underpinnings of AI, the practical applications of machine learning across industries, ethical considerations of autonomous systems, and the societal impacts of these disruptive technologies.
