Highly Anti‐Corrosive Performance of Poly(Vinylidene Fluoride‐Hexafluoropropylene)/Boron Nitride Nanosheet/Polyimide Composite Coating

Abstract Polyimide (PI) is one of the most important engineering plastics, but its stability in aqueous environments is insufficient, which limits its anti‐corrosion efficiency. In this study, a novel P(VDF‐HFP)/SMT‐RS@BNNSs/PI composite coating is prepared by incorporating poly(vinylidene fluoride‐hexafluoropropylene) (P(VDF‐HFP)) and the exfoliated boron nitride nanosheets (BNNSs) which were highly co‐functionalized with two kinds of materials of the rosin and the soy‐maleic anhydride‐tannic acid adhesive molecules (SMT‐RS@BNNSs). The coatings are characterized in detail by using the XRD, FT‐IR, XPS, and SEM technologies. Electrochemical impedance spectroscopy (EIS) and polarization curve tests further evaluated the corrosion resistance of the coating. As results, the obtained P(VDF‐HFP)/SMT‐RS@BNNSs/PI coating with good adhesion (grade 1) to the low‐carbon steel plate displays a larger water contact angle of 93.10° compared to blank PI (75.5°) and SMT‐RS@BNNSs/PI (83.2°). The dispersed distribution and interaction of SMT‐RS@BNNSs can effectively reduce the phase separation between P(VDF‐HFP) and PI. Even after soaking in electrolyte for 15 days, the impedance modulus, corrosion current, and corrosion voltage of the P(VDF‐HFP)/SMT‐RS@BNNSs/PI coating are 1.568 × 10 10 Ω cm 2 , 4.612 × 10 −12 A cm −2 , and 0.325 V, respectively. These properties are superior to those of the PI and SMT‐RS@BNNSs/PI coatings. It is believed that the excellent anti‐corrosive performance of this PI‐based composite will broaden the application fields of PI materials.