Plastics unite to make unexpected metal-like compound

When laid side-by-side the two materials are physically unchanged, but the way electrons behave is subtly altered along the interface where the different materials are in close proximity, says Morpurgo. In tests, they tried cooling down the combined materials, expecting the odd behaviour to disappear because the two plastics become more insulating at lower temperatures.

Instead the interface became a better conductor, just as metals offer less resistance to electricity when they are cooled.