Enhanced corrosion protection with bipolar coatings incorporating modified graphene

Coating is always one of the most important methods for corrosion protection, to address the problem that the coating does not have the ion-blocking ability, this paper takes modified graphene as the filler and prepares a bipolar coating with an inner layer containing cetyltrimethylammonium bromide (CTAB)-modified graphene that is cation-selective and prevents the penetration of cations such as metal ions, while the outer layer containing sodium dodecylbenzene sulfonate (SDBS)-modified graphene is anion-selective and blocks the entry of anions such as Cl⁻. The 0.01 Hz impedance modulus value of the bipolar coating with graphene addition of 0.6 wt% (Ts0.6) was 5.88 × 10¹⁰ Ω·cm² after 84 days of immersion, with no significant modulus attenuation, and five orders of magnitude elevated the modulus value compared to acrylic urethane coatings commonly used for storage tanks. Ts0.6 can withstand a minimum of 280 °C and has an adhesive strength to the substrate of 11.08 MPa. With the increased amount of graphene, its adhesion decreases, but heat resistance improves.