A smart-sensing coating based on dual-emission fluorescent Zr-MOF composite for autonomous warning of coating damage and aluminum corrosion

A smart-sensing coating is developed by adding a dual-emission fluorescent zirconium metal-organic framework/rhodamine B composite (Zr-MOF@RhB) into the commercial epoxy resin coating, which can autonomously detect and distinguish the damage of surface coating and the corrosion of substrate aluminum. The orange-yellow fluorescence can be observed to identify the area of mild coating damage without metal corrosion, resulting from the cumulative release of Zr-MOF@RhB with the emission wavelength of 583 nm. In case of the occurrence of aluminum corrosion, the fluorescence color turns from orange-yellow to green, in which the emission behavior of Zr-MOF@RhB at 490 nm is greatly enhanced with the presence of Al3+ ions. The smart-sensing ability can availably and robustly operate in the conditions of long term, wide ranges of pH and temperature, and diverse interfering substances. This simple and powerful warning system relying on fluorescent MOFs would not only extend the practical applications of MOFs but also be a promising candidate for smart coating strategies.