Researchers at the University of Colorado Boulder are developing a new class of \u201centangled materials\u201d inspired by the surprising strength of a tangled ball of office staples.\u00a0<\/p>\n
\u200b\u200bMuch like a bird\u2019s nest or a burr, a cluster of staples gains its strength from geometric interlocking rather than chemical bonds. But it retains the ability to instantaneously transition back into a loose piece through targeted vibration.<\/p>\n
\u201cWe\u2019ve been playing around with the idea of building blocks and geometry for many years, but we started looking at interlocking, entangled particles only recently,\u201d said Professor Francois Barthelat, the leader of the Laboratory for Advanced Materials and Bioinspiration.<\/p>\n
\u201cWe are excited about the combination of properties we can get out of these systems, and we believe this technology has the potential to go in many directions,\u201d Barthelat added.<\/p>\n
Geometry of grip<\/p>\n
The work centers around \u201centanglement.\u201d Through this, researchers are mimicking natural structures, such as bird nests and bone minerals, to create ultra-strong manufactured materials.\u00a0<\/p>\n
Particle shape is key in this. As compared to smooth grains of sand that slide apart, specialized geometries allow individual pieces to physically intertwine.\u00a0<\/p>\n
This mechanical locking creates a cohesive link that provides structural integrity without the need for adhesives.<\/p>\n
\u201cLet\u2019s take sand as an example. Sand is smooth and convex-shaped, meaning it cannot interlock from grain to grain,\u201d Youhan Sohn, Ph.D. student, said. <\/p>\n
\u201cHowever, we found that if we change the shape of a grain of sand, we can drastically affect its behavior and mechanical properties, including the particle\u2019s ability to link with other particles,\u201d Sohn explained. <\/p>\n
For the study, Monte Carlo simulations<\/a> were used to analyze particle geometry. and identified that \u201ctwo-legged\u201d staple shapes provide the most effective mechanical interlocking.\u00a0<\/p>\n Instead of stacking loosely, these U-shaped particles hook and weave into a singular mass that stubbornly resists being pulled apart.<\/p>\n Physical testing revealed that these entangled particles possess a rare dual advantage, maintaining simultaneous tensile strength<\/a> and exceptional toughness.<\/p>\n Use of vibration<\/p>\n The real power of this material is in its response to a simple buzz.<\/p>\n Standard materials are permanent. For instance, a concrete bridge is there forever until it is smashed into dust. But Barthelat\u2019s entangled particles are different.<\/p>\n The material\u2019s standout feature is its capacity for rapid, reversible assembly controlled by vibrational patterns.\u00a0<\/p>\n Interestingly, the entanglement levels can be modulated on demand through these vibrations. Gentle frequencies can lock particles into a rigid structure, whereas more intense vibrations trigger the complete unraveling of the mass.<\/p>\n \u201cIt\u2019s a strange material because it\u2019s obviously not a liquid. However, it\u2019s also not quite solid. This opens new and intriguing engineering possibilities,\u201d Barthelat said. \u201cHandling a bundle of these entangled particles feels very remote and exotic.\u201d<\/p>\n Entangled materials<\/a> offer potential for sustainability and advanced technology, particularly in civil engineering and robotics.\u00a0<\/p>\n It could enable large-scale structures, such as bridges, to be \u201cunzipped\u201d and recycled rather than demolished. Eventually, this technology could support a circular economy.\u00a0<\/p>\n Furthermore, it could advance swarm robotics<\/a>, allowing fleets of small machines to interlock into functional tools and later disentangle to navigate tight spaces \u2014 a real-world parallel to the shape-shifting capabilities of cinematic sci-fi.<\/p>\n \u201cYes, kind of like that liquid metal T-1000 in Terminator 2, who can change shape to slide under a door and then transform back to a human\u2019s size on the other side,\u201d added<\/a> Barthelat. <\/p>\n The researchers are currently pushing the boundaries of their work by testing multi-legged particle shapes modeled after high-grip plant burrs to achieve even more powerful entanglement.\u00a0<\/p>\n