A hydrogel disc can increase 100 times in area when stretched, according to research by Lili Chen et al. This hydrogel is extremely stretchy, being able to stretch to around 15 times its initial length. This makes it one of the most elastic materials known and could have applications in robotic grippers or tendons. Hydrogels are made of long chain-like polymer molecules linked by water molecules, known for their stretchiness but often not returning to their original shape when stretched too much.
Lili Chen and her team at Tsinghua University in Beijing developed a new kind of hydrogel that is both stretchy and maintains its original shape. They inserted pearl-necklace chains into the hydrogel structure, made up of coiled polymer beads connected by a chain of carbon atoms. These chains can unfurl under strain and rewind when the strain is released. By drying out the hydrogel, the polymer chains were attracted to themselves, enabling the hydrogel to stretch to impressive lengths before returning to its original length.
In experiments, the researchers found that a 30-centimetre length of their hydrogel could stretch to nearly 5 metres before returning to its original size in a few seconds. A 2-centimetre-wide disc of the hydrogel could increase 100 times in area before returning to its original size. This versatile material was used to create inflatable robotic grippers capable of gently handling delicate objects like strawberries. These grippers were extremely damage resistant, able to withstand a person standing on them or being pierced with a needle.
Experts, such as Zehuan Huang at Peking University in China, note that this work represents a significant advancement in high-performance polymeric materials. The combination of stretchiness and elasticity in this hydrogel opens up new possibilities in both materials science and soft robotics. The research has the potential to inspire further developments in the utilization of hyper-elastic gels in various applications.