Stimulus Responsive Zeolitic Imidazolate Framework to Achieve Corrosion Sensing and Active Protecting in Polymeric Coatings

Abstract

Metal substrates beneath polymeric coatings are susceptible to localized corrosion, which could result in lifetime reduction and catastrophic failure without timely repair treatment. In situ detection of corrosion and repair coating defects are in high demand yet challenging to fulfill so far. Herein, we report a smart polymeric coating by integrating nanosensors into the coating matrix, which is capable of efficient corrosion sensing and active anticorrosion protecting. The nanosensors were constructed by zeolitic imidazolate framework encapsulated with the polyethylene glycol-tannic acid complex. The morphology, chemical constitution, and stimulus responsiveness of nanosensors were systematically analyzed. The generation of local corrosion beneath coating can be promptly sensed and reported by a conspicuous purple color derived from tannic-iron ion coordinates. Meanwhile, local electrochemical impedance spectroscopy results proved that the metal degradation process at the defected interface can be largely inhibited, exhibiting active anticorrosion property. Furthermore, the constructed smart coating possessed superior impermeability and long-term protective performance under simulated seawater and harsh salts spray conditions. This feasible and effective strategy based on simple nanosensors to engineer smart coatings paves a new way to develop high environmental adaptability protective materials with protecting, corrosion sensing, and self-healing functions.

Design of Nanostructured Protective Coatings with a Sensing Function

“…A high impedance modulus at a frequency of 0.01 Hz (|Z| 0.01 Hz ) indicates a high corrosion resistance. 48 |Z| 0.01 Hz of coatings A141, A151, C241, and C351 decreased after immersion in the saline solution after 60 days (Figure 4b). Indeed, these coatings contained less BTA than coatings A161 and C361.…”

“…Bode impedance and phase plots (Figure S6a–d) were prepared for different immersion times in a 3.5 wt % NaCl aqueous solution. A high impedance modulus at a frequency of 0.01 Hz (| Z | 0.01 Hz ) indicates a high corrosion resistance . | Z | 0.01 Hz of coatings A141, A151, C241, and C351 decreased after immersion in the saline solution after 60 days (Figure b).…”

“…In addition, an interesting feature to be introduced in coatings for anticorrosion is corrosion sensing so that metallic structures can be replaced before critical damage. , This has been achieved by encapsulating various dyes in particles ,,,− or fibers that were subsequently embedded in coatings. The coatings displayed then a change of color or an increase/decrease in fluorescence intensity upon change of pH value or the presence of metal ions as a consequence of the corrosion process.…”

Photothermal-Responsive Wormlike Polydopamine-Wrapped Ethylene-Vinyl Acetate Copolymer toward Triple-Action Self-Healing Anticorrosion Coating

“…9,10 Especially, applying a polymeric coating is one of the most common strategies to protect metal from corrosion, which is based on the formation of barrier layers between metal and aggressive ions. 11,12 Since the release of volatile organic compounds (VOCs), the application of conventional solvent-based polymer coatings is limited in an increasing number of industries. 13 Accordingly, waterborne epoxy coating (WEP) has emerged as a promising material for metal protection.…”

“…25−27 Due to simple preparation, independent to resin types and uninjurious to coating integrity, the effectiveness of embedding containers or capsules into coatings has been illustrated on suppressing localized corrosion. 12,28 However, many encapsulated healing agents including dicyclopentadiene, linseed oil, alkoxysilane, tung oil, silyl ester, and isocyanates are liquid at room temperature and cannot be stable in practical anticorrosion coatings. 27,29−31 Therefore, the solid healing agents become ideal fillers for constructing high-performance SHACs.…”