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<\/div>A hydrogel disc can increase 100 times in area when stretched<\/p>\n
Lili Chen et al.<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
A hydrogel that can stretch to around 15 times its initial length is one of the most elastic materials yet known and could be used for robotic grippers or tendons.<\/p>\n
Hydrogels, which are made of long chain-like polymer molecules linked by water molecules, are well-known for their stretchiness<\/a>, but they often don\u2019t return to their original shape when they are stretched too much.<\/p>\n Lili Chen<\/a> at Tsinghua University in Beijing and her colleagues have developed a new kind of hydrogel that is extraordinarily stretchy but maintains its original shape. They modified the typical hydrogel structure by inserting what they call pearl-necklace chains, which consist of coiled polymer beads connected by a chain of carbon atoms. These can unfurl under strain and rewind when the strain is released.<\/p>\n To make these chains, Chen and her team dried out a hydrogel so that the polymer chains were attracted to themselves, when normally they would be pulled more strongly by the water molecules.<\/p>\n They found that a 30-centimetre length of their hydrogel could stretch to nearly 5 metres before returning to its original length in a few seconds. A 2-centimetre-wide disc of the hydrogel, pulled outwards in all directions, could increase 100 times in area before returning to its original size.<\/p>\n <\/p>\n The researchers also built inflatable robotic grippers from the hydrogel, designed to gently handle fragile things<\/a>. These were able to pick up objects such as strawberries and were extremely damage resistant, continuing to work after a person stood on them or pierced them with a needle.<\/p>\n \u201cHydrogels are usually stretchy but not that elastic, while this gel combines both properties to make ultra-deformable and hyper-elastic materials.\u201d says Zehuan Huang<\/a> at Peking University in China, who wasn\u2019t involved in the study. \u201cUndoubtedly, this work represents a major breakthrough in high-performance polymeric materials, and will inspire substantial interest into exploitation of hyper-elastic gels in soft robotics.\u201d<\/p>\n Topics:<\/p>\n<\/section><\/div>\n