Novel hydrogel displays extreme elasticity

Nature : Hydrogels are polymers whose structure lets them absorb large amounts of water to become a jelly-like material. Most hydrogels break very easily when stressed. Zhigang Suo and his team of researchers at Harvard University combined two polymers into a single material that can be stretched up to 20 times its original length without breaking. The trick is that one of the polymers creates ionic bonds while the other creates covalent bonds. When the material is stretched, the weaker ionic bonds break, letting the hydrogel stretch, and the stronger covalent bonds pull it back to its original shape. Fracturing the resulting substance requires approximately the same amount of energy as does standard rubber.