A hydrogel disc developed by Lili Chen and her team at Tsinghua University in Beijing is capable of increasing 100 times in area when stretched. This hydrogel is one of the most elastic materials known, able to stretch to around 15 times its initial length. The key to this material’s unique properties lies in the insertion of pearl-necklace chains into its structure.
These chains are made of coiled polymer beads connected by a chain of carbon atoms and can unfurl under strain before rewinding when the strain is released. By drying out the hydrogel so that polymer chains were attracted to themselves rather than water molecules, the researchers were able to create a hydrogel that could stretch to nearly 5 meters before returning to its original length.
The researchers also created inflatable robotic grippers from this hydrogel, designed for delicate object handling like strawberries. These grippers are extremely durable and resistant to damage, able to withstand being stood on or pierced with a needle. Zehuan Huang at Peking University commended the work, stating that this hydrogel represents a major breakthrough in high-performance polymeric materials and will inspire interest in using hyper-elastic gels in soft robotics.