Organic coating is the most convenient and effective technique for protecting metallic materials from corrosion, especially the epoxy coating.
However, current epoxy coatings were vulnerable to physical and chemical damage. The development of smart self-healing epoxy coatings is significant in the field of functional anti-corrosion coatings.
Recently, Associate Professor ZHANG Binbin of Prof. DUAN Jizhou's team from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) reported a thermally-triggered self-healing epoxy coating towards sustained corrosion protection.
The study was published in Journal of Materials Research and Technology on Feb. 11.
The researchers used 2-aminophenyl disulfide (APD) as a hardener for the design and construction of a novel self-healing epoxy coating (EAPD coating) to recover the micro-scale mechanical scratches. APD molecules possess "recycling" property by breaking and re-forming disulfide bridges in a controlled manner, such as moderate temperature, catalysts, and ultraviolet radiation.
Aromatic disulfide exchange and aromatic disulfide bridges of APD molecules are versatile and relatively easy to incorporate into polymer networks, contributing for the formation of dynamic EAPD resin networks with reversible aromatic disulfide crosslinks.
"The developed EAPD coating exhibits superior thermally-triggered self-healing performance with mechanical scratches completely self-repaired after 20 min at 80 °C," said Dr. ZHANG.
According to the electrochemical impedance spectroscopy results, the impedance modulus values at low frequency of the scratch-healed EAPD coating were found to be close to the initial EAPD coating, which showed that the corrosion resisting property was enhanced and recovered through thermally-triggered structural and chemical self-healing process.
"The self-healing epoxy coating may provide a new design strategy for the development of smart and multi-functional protective coating materials with intriguing properties," said Dr. ZHANG.
The self-repairing behavior and anti-corrosion mechanism of the as-prepared self-healing epoxy coating (Image by IOCAS)
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