A novel polymer composite coating with high thermal conductivity and unique anti-corrosion performance

•A novel highly thermally conductive and anti-corrosion polymer coating was prepared.•The coating can protect metal heat exchanger from corrosion while maintaining the high heat conduction performance.•Modified G served as thermally conductive bridges to connect the adjacent BN for forming heat conduction pathways.•Phe modified 2D BN and G endowed the coating with unique multiple barrier effect.•The enhanced interfacial compatibility was conducive to both thermally conductive and anti-corrosion performance. Corrosion prevention and heat conduction are the key issues of numerous industrial equipment. Unfortunately, they are generally mutually exclusive properties for various heat exchangers-improving one capability usually causes decreased capability in another. Herein, a novel highly thermally conductive and anticorrosive coating for heat exchanger protection is reported, in which L-phenylalanine (Phe) modified boron nitride (BN) and graphene (G) sheets not only form heat conduction pathways, but also have unique multiple barrier effects. And the modified fillers exhibit improved interfacial compatibility with epoxy (EP). These factors confer the BN/G/Phe/zinc phosphate (ZP)/EP coating with a high thermal conductivity of 1.63 W/(m·K), which enhances 641% than that of EP coating (0.22 W/(m·K)), and could significantly reduce the heat transfer coefficient loss of the coated heat exchanger from 9.47% (when EP coating is coated) to 1.39% according to the theoretical calculations. Moreover, further combined with the corrosion-inhibiting film formed by ZP, the impedance modulus at 0.01 Hz of the BN/G/Phe/ZP/EP coating always maintains above 1011ohm·cm2 during 150 days of immersion in 3.5 wt% NaCl solution. The mechanism of the enhanced heat conduction and anti-corrosion performance of the coating are vividly discussed in detail. This work is of great significance to the development of new functional coatings with both high heat conduction and unique corrosion prevention capabilities.