Key Highlights:
- Researchers have created a jelly-like substance that can endure the equivalent of an elephant treading on it and totally recover to its previous shape.
- The ‘super jelly’ has a wide range of possible uses, including soft robotics, bioelectronics, and even as a biological cartilage replacement.
- The scientists used specialized guest molecules for the cuffs to create their glass-like hydrogels.
Indestructible Jelly
Researchers have created a jelly-like substance that can endure the equivalent of an elephant treading on it and totally recover to its previous shape.
Despite its high water content, the soft-yet-strong material created by a team at the University of Cambridge looks and feels like a squishy jelly when crushed, but functions like an ultra-hard, shatterproof glass when compressed.
The non-water element of the material is a network of polymers kept together by reversible on/off interactions that govern the mechanical characteristics of the material. This is the first time that such high compression resistance has been put into a soft material.
The ‘super jelly’ has a wide range of possible uses, including soft robotics, bioelectronics, and even as a biological cartilage replacement.
The development process
The molecular structure of a substance determines how it behaves – whether it is soft or solid, fragile or robust. Stretchy, rubber-like hydrogels offer a variety of intriguing qualities that make them a hot study topic, such as toughness and self-healing capabilities, but creating hydrogels that can endure compression without crushing is difficult.
“In order to develop materials with the mechanical qualities we seek, we employ crosslinkers, which are two molecules connected by a chemical connection,” explained the study’s first author, Dr. Zehuan Huang of the Yusuf Hamied Department of Chemistry.
“We use reversible crosslinkers to make soft and stretchy hydrogels, but making a hard and compressible hydrogel is difficult and designing a material with these properties is completely counterintuitive.”
The researchers employed barrel-shaped molecules called cucurbiturils to create a compressible hydrogel in the lab of Professor Oren Scherman, who spearheaded the study. Cucurbituril is the crosslinking molecule that, like a molecular handcuff, binds two guest molecules in its cavity. The researchers created guest molecules that choose to stay within the cavity for longer periods of time than usual, keeping the polymer network securely bonded and allowing it to endure compression.
The scientists used specialized guest molecules for the cuffs to create their glass-like hydrogels. Changing the chemical structure of the guest molecules inside the handcuff caused the material’s dynamics to ‘slow down,’ with the mechanical performance of the final hydrogel varying from rubber-like to glass-like states.
“People have spent years developing rubber-like hydrogels, but that’s just half of the picture,” Scherman explained. “By revisiting classic polymer physics, we’ve generated a new class of materials that cover the entire spectrum of material characteristics, from rubber-like to glass-like, completing the picture.” The material was employed by the researchers to create a hydrogel pressure sensor for real-time tracking of human activities such as standing, walking, and leaping.
