Crystalline polyvinylidene chloride embedded in epoxy composite coating for oxygen gas barrier and anti-corrosion

The corrosion of metals is extremely serious in high-pressure air injection oil recovery, compressed air energy storage and other harsh oxygen (O2) environments. Herein, epoxy resin (EP) used as the continuous phase, vinylidene chloride (VDC) and methacrylate (MA) copolymer (denoted as PVDCM) as the dispersed phase, an EP/PVDCM composite coating containing crystalline phase was prepared by spin-coating method. The VDC chains were arranged regularly into dense crystalline regions under the action of polar covalency, which was conducive to extending the permeability path and reducing the permeation of O2 and corrosive media. Meanwhile, EP/PVDCM composite coating had good hydrophobicity, which can further prevent the infiltration of O2 and corrosive media dissolved in water. In addition, EP improved the poor adhesion of crystalline polymers. The hydrogen bonding between MA and EP enhanced the interface bonding strength in the coating and lessened the penetration rate of O2 and corrosive media into the interface between the coating and the steel plate. Results showed that the |Z|0.01Hz value of EP/PVDCM composite coating still remained above 1010 ohm·cm2 after immersed in 12 wt% NaCl solution at 90 °C for 30 days. The O2 permeability coefficient decreased by 89.65% compared with pure EP. This research provides a novel direction for the domains of filler-free anti-corrosion and O2 barrier coatings and possesses a superior industrial application prospect.