A group of scientists recently reported the development of a new rubber-like solid material with startling properties. It has the ability to absorb and release massive amounts of energy. It’s also programmable. This new material, when combined, has a lot of potential for a broad range of applications, from allowing robots to have greater power without requiring more energy to new helmets and protective coverings that can disperse energy much more rapidly.
“Think of a rubber band,” says Alfred Crosby, a senior author on the research and a professor of polymer science and engineering at UMass Amherst. “You draw it back, and it flies across the room when you let go. Consider a super-rubber band. You activate more energy contained in the material when you extend it beyond a specific point. This rubber band flies for a mile if you let go of it.”
This hypothetical rubber band is composed of a novel metamaterial, which mixes an elastic, rubber-like substance with microscopic magnets implanted in it. Metamaterials are materials that have been designed to exhibit properties not present in naturally occurring materials. This novel “elasto-magnetic” material uses a physical phenomenon called phase shift to dramatically increase the amount of energy it can emit or absorb.
When a substance transitions from one state to another, such as water to steam or liquid concrete to a sidewalk, a phase shift occurs. Energy is emitted or absorbed whenever a substance changes phase. A phase shift may occur from one solid phase to another, and it isn’t restricted to transitions between liquid, solid, and gaseous phases. A phase shift that releases energy may be used as a source of energy, but acquiring enough of it has always been a challenge.
“You have to create a new structure at the molecular or even atomic level to increase energy release or absorption,” Crosby adds. However, doing so is tough, and doing it in a predictable manner is considerably more difficult. “We have solved these obstacles, and we have not only built new materials, but we have also established the design algorithms that enable these materials to be programmed with certain behaviors, making them predictable,” Crosby adds of metamaterials.
The team was inspired by some of nature’s lightning-fast reflexes, such as Venus flytraps and trap-jaw ants clamping shut their jaws. “We’ve moved it to the next level,” says Xudong Liang, the paper’s main author, who is now a professor at Harbin Institute of Technology, Shenzhen (HITSZ) in China and performed this study while a postdoc at UMass Amherst. “We can regulate the phase transitions of this metamaterial by integrating small magnets within the elastic material. We can construct the metamaterial to do precisely what we want it to do, either absorbing the energy from a massive hit or releasing enormous amounts of energy for explosive movement, since the phase change is predictable and repeatable.”
This study, which was funded by the United States Army Research Laboratory and the United States Army Research Office, as well as the Harbin Institute of Technology, Shenzhen (HITSZ), has potential in any situation requiring high-force hits or lightning-quick reactions.