Organic coating is the most convenient and effective technique for protecting metallic materials from corrosion, epoxy coatings, in particular, are commonly utilized in a variety of fields resulting from their superior mechanical properties, high adhesion strength, good heat resistance, and high electrical resistance.

However, current epoxy coatings were vulnerable to physical and chemical damage during real-world service, the development of smart self-healing epoxy coatings is becoming one of the research hotspots 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. 

Researchers use 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 etc.

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 (EIS) results, the impedance modulus values at low frequency of the scratch-healed EAPD coating is found to be close to the initial EAPD coating, verifying the corrosion resisting property was significantly enhanced and recovered through thermally-triggered structural and chemical self-healing process.

"The created self-healing epoxy coating is thought to provide a new design strategy for the development of smart and multi-functional protective coating materials with intriguing properties," said Dr. ZHANG.

This work was financial supported by the Project of Innovation Development Joint Funds supported by Shandong Provincial Natural Science Foundation, and the Youth Innovation Promotion Association Chinese Academy of Sciences.

The self-repairing behavior and anti-corrosion mechanism of the as-prepared self-healing epoxy coating

Binbin Zhang*, Hao Fan, Weichen Xu, Jizhou Duan. (2022). Thermally triggered self-healing epoxy coating towards sustained anti-corrosion. Journal of Materials Research and Technology, 17, 2684-2689.

ZHANG Binbin

Institute of Oceanology

E-mail: zhangbinbin@qdio.ac.cn 

(Editor: ZHANG Yiyi)