Pourbaix sensors in polyurethane molecular logic-based coatings for early detection of corrosion

The cost of corrosion to the world economy is estimated to be in excess of US$2.5 trillion per year. Herein we present a strategy for the early detection of corrosion using purposely designed molecules with on-board parallel processing in a polyurethane coating on mild steel. The proof-of-concept is demonstrated with perylenediimide and 4-amino-1,8-naphthalimide-based molecules that function as H+, Fe3+-driven AND logic gates for high acidity and oxidising conditions. The onset of corrosion is detected by an enhanced yellow-green fluorescence (>500 nm). The extent of fluorescence enhancement is viewed by confocal fluorescence microscopy. The applicability of logic-based molecules represents a method for the non-destructive and early detection of corrosion long before the metal surface suffers any permanent damage.