CARBON nanotubes have been bonded to the molecular backbone of a polymer for the first time. The feat could one day lead to a new generation of tough, lightweight composites for use in cars and aircraft.

Because carbon nanotubes are 30 times stronger than steel yet five times less dense, chemists have been keen to use them to reinforce plastics. But simply mixing them in melted plastic does not work, since no bonds form between the tubes and the long chains that make up a polymer. "It means a force on the composite material is not transferred to the nanotubes, so they don't provide any reinforcement," says Yurii Gun'ko, a chemist at Trinity College Dublin in Ireland.

Now Gun'ko and his team have worked out a way to chemically bond nanotubes to a polymer. Their trick is to use the imperfections in nanotubes as bonding points. Nanotubes, which comprise rolled-up ...