Epoxy-matrix polyaniline/ p -phenylenediamine-functionalised graphene oxide coatings with dual anti-corrosion and anti-fouling performance.

This research work reports on the anti-corrosion and anti-fouling properties of epoxy (E) coatings reinforced with polyaniline (PANI)/ p -phenylenediamine-functionalised graphene oxide (PGO) composites. The mass ratio of graphene oxide/ p -phenylenediamine in any PGO was assumed to be 1 : 1, but different PANI-PGO composites containing various loadings of PGO were prepared. An ultrasonic-assisted in situ polymerization method was employed to produce PANI-PGO at low temperature (0 °C). Several analytical and microscopical techniques, i.e. , Fourier-transfer infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM), were used to confirm that PANI-PGO composites were successfully synthesized. The epoxy-based coatings (E/PANI-PGO ( x ), x = 0.05-0.4 g) were applied by brushing them onto carbon steel substrates, which exhibited dual anti-corrosion and anti-fouling performance. Electrochemical impedance spectroscopy (EIS) results show that E/PANI-PGO (0.2) has the highest corrosion resistance (8.87 × 10 6 Ω cm 2 ) after 192 h of immersion in 3.5 wt% NaCl amongst all the coatings compared with neat epoxy (1.00 × 10 4 Ω cm 2 ) and E/PANI (6.82 × 10 3 Ω cm 2 ). Efficient antifouling performance at the macroscopic level under simulated marine conditions was observed for the epoxy-based PANI-PGO coatings with a range of PGO compositions, in particular for the 0.1 and 0.2 g PGO coatings.