Zinc oxide grown on boron nitride via polydopamine as nano-pigment to enhance the active/passive protective properties of silicone-epoxy coatings

In harsh marine environments, the long-term protection performance of organic coatings is not ideal. Based on this, a strategy for constructing a triple-functional nano-pigment was proposed. Zinc oxide (ZnO) grown on boron nitride (BN) with polydopamine (PDA) as an interface layer (PDA-BN@ZnO nano-pigment) was prepared. This strategy not only avoided the accumulation of BN but also improved the interface compatibility between nanopigment and silicon-epoxy resin. Characterization analyses validated that ZnO had been successfully grown onto PDA-modified BN nanosheets. Polarisation curves obtained in the solution phase showed that compared with the Al-alloy immersed in pure 3.5 wt% NaCl solution, the introduction of PDA-BN@ZnO caused icorr to decrease from 2.11 x 10(-5) A/cm(2) to 9.47 x 10(-9) A/cm(2). Combined with the significant enhancement of the low-frequency impedance modulus (|Z| (0.01 Hz)) of the scratched PDA-BN@ZnO/SE coatings, the effective corrosion inhibition of the prepared nano-pigment was demonstrated. In addition, |Z| 0.01Hz of PDA-BN@ZnO/SE composite coating after immersion for 60 days was as lhigh as 10(10) Omega center dot cm(2) with only about 0.3 orders of magnitude lower than the initial value. The excellent protective properties of the composite coating were due to the synergistic effects of improved barrier properties, chloride ion retention and corrosion inhibition.