Scientists Create New Type of Matter
A team of scientists from Caltech has introduced a novel form of matter, dubbed polycatenated architected materials (PAMs). This unique material, not found in nature, features a chainmail-like design with intertwined rings instead of fixed particles commonly seen in crystalline structures. Due to its semi-liquid, semi-solid properties, PAMs excel at absorbing energy, making them ideal for protective gear and soft robotics applications. The innovative use of chainmail is gaining attention in the scientific community.
Recently, researchers at Northwestern University crafted molecular chainmail using mechanical polymer bonds. Now, a separate team led by Caltech scientists has developed PAMs, a form of matter that bridges the gap between liquid and solid states. These materials, resembling interconnected links akin to chainmail armor, offer the benefits of both solid and liquid substances, allowing them to withstand a wide range of stresses. This versatility has significant implications for various applications, such as protective gear, biomedical materials, and robotics. The detailed findings of this new chainmail-like structure were published in the journal Science.
“This new type of matter, PAMs, represents a significant advancement,” remarked Chiara Daraio, the senior author of the study at Caltech. “The traditional distinction between solid materials and granular matter is well-established. Solid materials are often described as crystalline lattices, comprised of discrete particles capable of free movement and sliding relative to each other.”
Despite their technical complexity, PAMs are visually intriguing and offer playful potential. These materials can be crafted into diverse shapes and sizes. For the study, the team created cube- and sphere-shaped structures measuring approximately 2 inches in diameter. The design process involved computer modeling to mimic crystalline structures, replacing fixed particles with entangled rings or cages with multiple sides.
Following 3D-printing using acrylic polymers, metals, and nylon, the team subjected this “new form of matter” to various stress tests. Lead author Wenjie Zhou, a postdoctoral researcher at Caltech, explained, “We conducted compression tests, gradually increasing the pressure applied to the objects. Subsequently, we tested shear stress, a lateral force akin to attempting to tear the material apart. Finally, we performed rheology tests to observe the response to twisting motions, varying from slow to rapid and forceful.”
Under shear stress, PAMs exhibited liquid-like behavior due to the coordinated movement allowed by their chainmail-like lattice structure. However, when compressed, they displayed solid properties. Scientists are only beginning to explore the potential applications of PAMs, acknowledging their exceptional ability to dissipate energy by enabling individual elements to slide, rotate, and reorganize relative to each other.
The distinctive attributes of chainmail have been recognized by mankind for over 2,000 years, yet it is only in recent times that scientists are beginning to fully comprehend the vast array of potential uses for this age-old creation.
