Researchers have developed a new jello-like material that can withstand the pressure equivalent to being stood on by an elephant, and still return to its original shape.
What makes it even more remarkable is the material—a type of hydrogel—is made of 80 percent water.
“At 80 percent water content, you’d think it would burst apart like a water balloon, but it doesn’t: it stays intact and withstands huge compressive forces,” University of Cambridge, Department of Chemistry researcher Professor Oren A. Scherman, who led the development of the material said in a press statement. “The properties of the hydrogel are seemingly at odds with each other.”
The material’s high water content makes it feel and appear like squishy jello, but when pressure is introduced the material hardens, acting like an ultra-hard shatterproof glass.
Uses for the material could include the development of soft robots that could perform tasks too delicate for traditional “hard” robots. The material could even have important applications in medicine, functioning as cartilage replacement for biomedical use.
The key to the super jello’s strength under compression is its non-water component. The material contains a network of polymers—large stringy chains of repeating molecules—which are held together by reversible interactions that control the material’s mechanical properties.
This is the first time that such resistance to pressure has been introduced to a hydrogel, a material known for its ability to hold a large amount of water while maintaining the structure. That makes this new super jello special even in a range of materials already known for their unique properties.
“The way the hydrogel can withstand compression was surprising, it wasn’t like anything we’ve seen in hydrogels,” University of Cambridge researcher Dr. Jade McCune said. “We also found that the compressive strength could be easily controlled through simply changing the chemical structure of the guest molecule inside the handcuff.”
The way materials behave and if they are soft or firm, brittle or strong is due to their molecular structure. Rubber-like hydrogels demonstrate toughness and self-healing capabilities while still being flexible and stretchy. But thus far, making hydrogels that can withstand being compressed without getting crushed is a challenge.
Behind the super jello’s resistance to compression are barrel-shaped molecules called cucurbiturils that make up its constituent polymers. When compressed, cucurbiturils can hold molecules with their cavities like a pair of molecular handcuffs.
These molecules can stay within the cavity for an extended time, meaning the links between molecules remain intact. The change between glass-like and jello-like is the result of this slow-down in the dynamics of the material. It means the material can “bounce back” to its original shape and consistency when the pressure is relieved.
“To the best of our knowledge, this is the first time that glass-like hydrogels have been made. We’re not just writing something new into the textbooks, which is really exciting, but we’re opening a new chapter in the area of high-performance soft materials,” Yusuf Hamied Department of Chemistry researcher Dr. Zehuan Huang said.