Staple-Shaped Particles Create Reversible, Adaptable Material

Scientists have developed a new material using staple-shaped particles that can rapidly switch between a solid and a loose collection. This material can be strong and flexible, or it can fall apart in seconds. Researchers at the University of Colorado at Boulder's Paul M. Rady Department of Mechanical Engineering led this work.

The team found that staple-shaped particles can tangle together to create a material that is both strong and flexible. Unlike conventional materials, these particles can be locked into a sturdy structure or rapidly unraveled using vibrations. This behavior could lead to new applications in construction and robotics.

The research focuses on entanglement, where particles intertwine and form connections. Natural examples include bird nests and bones. The scientists used Monte Carlo simulations to study how different particle shapes interact. They aimed to identify a geometry that would maximize entanglement.

Their findings, published in the *Journal of Applied Physics*, showed that a two-legged, staple-like particle produced the highest degree of entanglement. This shape offered both high tensile strength and toughness, properties often difficult to combine. The material's ability to rapidly assemble and disassemble using vibrations makes it unique.

This technology could support sustainable construction by enabling recyclable buildings that can be taken apart and reused. It also has potential applications in robotics, such as swarm robots that can entangle for tasks and then disentangle. The team is now experimenting with new particle designs that include additional protruding “legs” to create stronger entanglement effects.