Scientists at Tsinghua University in Beijing have created a hydrogel that can increase in area by 100 times when stretched. This hydrogel is one of the most elastic materials known and can stretch to around 15 times its initial length. Hydrogels are made of polymer molecules linked by water molecules and are known for their stretchiness, but they often do not return to their original shape when overstretched.
Lili Chen and her colleagues achieved this breakthrough by inserting pearl-necklace chains into the hydrogel structure, made of coiled polymer beads connected by a chain of carbon atoms. These chains can unfurl under strain and rewind when the strain is released. To create these chains, the researchers dried out the hydrogel so that the polymer chains were attracted to themselves rather than to water molecules.
Their hydrogel could stretch to nearly 5 meters before quickly returning to its original length. A 2-centimeter-wide disc of the hydrogel could increase 100 times in area before returning to its original size. The researchers also created inflatable robotic grippers from the hydrogel, designed to handle delicate objects like strawberries. These grippers were extremely damage resistant, able to withstand being stood on or pierced with a needle.
Zehuan Huang at Peking University praised 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.
