A hydrogel disk can expand 100 times when stretched. This elastic material is one of the most stretchable known, capable of stretching to about 15 times its initial length. It can be used in robotic grippers or tendons. Hydrogels are made of polymer molecules linked by water molecules and are known for their stretchability, but often do not return to their original shape when stretched.
Researchers at Tsinghua University in Beijing have developed a new type of hydrogel that is both stretchable and retains its original shape. They achieved this by inserting chains of pearl necklaces into the hydrogel structure, made of coiled polymer beads connected by a chain of carbon atoms. These chains can uncoil under load and rewind when the stress is released.
To create these chains, the researchers dried the hydrogel so that the polymer chains were attracted to themselves rather than water molecules. They found that their hydrogel could stretch to almost 5 meters before quickly returning to its original length. A 2-centimeter-wide disc of hydrogel could expand 100 times in surface area before returning to its original size.
The researchers also created inflatable hydrogel robotic grippers designed to handle delicate objects like strawberries. These grips were extremely resistant to damage, being able to withstand being stood on or punctured by a needle. Zehuan Huang of Peking University praised the work, stating that this hydrogel represents a major breakthrough in high-performance polymer materials and will stimulate interest in the use of hyperelastic gels in soft robotics.
In summary, a new type of stretchable hydrogel has been developed by researchers at Tsinghua University in Beijing that retains its original shape after stretching. The hydrogel was made using pearl necklace chains inserted into a coiled polymer bead structure connected by carbon atoms, which allowed it to uncoil under load and rewind when stress was released