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Your eyes aren’t deceiving you — you just watched a metal ball bounce off a sliver of jelly. But you wouldn’t put this jelly in a sherry trifle: it is a sophisticated hydrogel developed by Zhigang Suo, a materials engineer at Harvard University in Cambridge, Massachusetts, and his colleagues1. A hydrogel is a network of polymers that soaks up lots of water to form a jelly-like material. But most shatter easily and don’t stretch far without breaking. Some of the toughest hydrogels are used to make soft contact lenses, and researchers want to make them more robust, for use in...

American chemists have made molecular 'daisy-chains' containing threaded rings that can be pulled taut or slackened by chemical stimuli. The polymers are a step towards making materials that stretch or contract on demand, and show great potential for applications such as actuators in nanomachinery or designing artificial muscles. 'Artificial muscle tissue is still a long way off, but we are starting to demonstrate the kind of systems where it could be possible,' says Robert Grubbs, who led the work at the California Institute of Technology, US. Grubbs won the Nobel Prize in Chemistry in 2005 for his work on olefin metathesis reactions, which allow carbon-carbon...

Skin is spectacular stuff. Nick it with a razor or scrape it on the sidewalk, and it heals itself quickly. Synthetic materials are another story, although it’s not for lack of effort on the part of scientists. Chemists have tried for years to develop self-healing polymer coatings for use on cars, furniture and other objects. Recent efforts use microspheres containing bonding chemicals. These tiny capsules are embedded in the coating. When a crack or scratch occurs, the spheres break and the chemicals flow into the void, patching it. Biswajit Ghosh and Marek W. Urban of the University of Southern Mississippi...