To understand what makes smart paint so smart, consider normal dumb paint, typically made up of two components: pigment particles, which provide color, and a polymer, which functions both as a dispersant (keeping the particles from clumping) and a glue. When water seeps underneath a coat of paint, the underlying metal corrodes. But smart paints prevent seepage and NJIT scientists are considering several strategies for creating them. One of the most promising would involve embedding minuscule carbon nanotubes in the polymer to make it electrically conductive. Also embedded in the polymer would be tiny paint-filled capsules, a micron or so wide. A crack in the paint surface would change
its electrical properties. Built-in sensors would pinpoint the problem and the capsules would open automatically, flowing into the crack and sealing the surface from further damage. To make color change possible, the scientists would add specially designed molecules that are sensitive to electrical signals. Send the right signal and these molecules would light up, overriding the background color -- say, brown -- with their own green or red hue.