“A new temperature-sensitive varnish that can be applied to road surfaces to visually warn drivers about dangerous conditions. the varnish is made of a polymer containing a thermochromic pigment. the same type of coating is already used to make bath thermometers & frozen food packaging that responds to temperature change. however, it is the first time such a coating has been used to monitor road temperatures.”

Intelligent paint turns roads pink in icy conditions
via infosthetics.com