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• EPPVA-grafted-PANI (EPPVA-g-PANI) were prepared by graft polymerization. • The balance between phosphorylation, grafting reaction and properties were explored. • EPPVA-g-PANI displayed better compatibility with waterborne alkyd resin (WAR). • WAR/EPPVA-g-PANI showed enhanced long-term corrosion resistance. Phosphorylated poly(vinyl alcohol) (PPVA) was demonstrated to be more effective to improve the dispersion stability of polyaniline (PANI). Phosphate groups also can improve corrosion resistance, but they may spatially interfere with graft reaction of PANI onto PPVA. Therefore, it is of great significance to explore the balance between phosphorylation degree, graft reaction and composite performance. Here, EPPVA-grafted-PANI (EPPVA-g-PANI) dispersions were prepared by chemical grafting polymerization of aniline on the epichlorohydrin modified PPVA (EPPVA) with different degree of phosphorylation (DP). It was found that DP has a considerable effect on microstructure, rheological behaviors, as well as the compatibility between EPPVA and PANI. Enhanced interactions and compatibility were demonstrated for EPPVA-g-PANI-8.00 %, resulting in the increase of tensile strength from 26.84 to 38.62 MPa. As-prepared EPPVA-g-PANI dispersions can be directly blended with waterborne alkyd resins (WAR) without complex post-process to fabricate high-performance WAR/EPPVA-g-PANI nanocomposites. Compared with WAR, the impedance modulus of WAR/EPPVA-g-PANI increased from 8.81×104 to 3.03×1010 Ω·cm2, corrosion current density decreased to 3.02×10−8 from 1.78×10−6 A·cm−2. Additionally, only one time constant was detected after 480 h immersion, further demonstrating excellent long-term corrosion resistance for WAR/EPPVA-g-PANI. [ABSTRACT FROM AUTHOR]

In this study, we aimed to enhance the anticorrosion performance of composite coatings by introducing polyhedral oligomeric silsesquioxane (POSS)-grafted graphene oxide surfaces. These surfaces were modified to achieve super-hydrophobicity and a self-fixing effect. The modified material was employed to enhance the corrosion resistance of fluorinated polyimide (FPI) composite coatings composed of graphene oxide (GO) grafted by POSS (POSS-GO). The resulting composite coating exhibited substantially improved corrosion resistance compared to a pure FPI coating. The impedance modulus (|Z| 0.01 Hz) of the 0.3 wt% FPI/POSS-GO coating was approximately 2.57 × 1011 Ω·cm2, which was greater than that of the pure FPI coating by approximately five orders of magnitude. The enhanced performance can be attributed to the synergistic interaction between the intrinsically hydrophobic polyimide matrix polymer, which acts as a barrier, and the POSS-GO fillers with their superhydrophobic and self-fixing characteristics. Notably, these properties remained effective even after subjecting the coatings to a 3.5 wt% NaCl solution during a 45-day salt spray test. These findings have significant implications for the development of cost-effective anticorrosion coatings for metal substrates. In this study, we successfully developed a 0.3wt%FPI/POSS-GO composite coating by spraying method, and cured upon high-temperature thermal imidization. Furthermore, the |Z| 0.01 Hz value of 0.3wt%FPI/POSS-GO coating was 1.14 × 1011 Ω·cm2, after a 45-day neutral salt corrosion test. The excellent corrosion resistance of the composite coatings was attributed to the improved barrier property provided by the well-dispersed POSS-GO with self-fixing and hydrophobicity. Last but not least, we could boldly predict that this is a long-term corrosion resistant coating that can be applied in complex service environments, such as marine, alternating wet and dry. [Display omitted] • A fluorinated polyimide-based super anti-corrosion coating was prepared. • An appropriate amount of POSS-GO effectively improved the compactness and heat resistance of the coating. • The self-fixing effect of POSS-GO promotes its dispersion stability in FPI resins, providing better barrier performance. • The FPI/POSS-GO composite coating holds great potential for long-term corrosion protection. • Anti-corrosion mechanisms of the coatings were revealed. [ABSTRACT FROM AUTHOR]

The ecofriendly waterborne alkyd coatings generally compromise the coating performance. Incorporation of polyaniline into alkyd to form nanocomposites can improve the corrosion resistance; however, the uniform distribution of polyaniline (PANI) within the alkyd resin remains a challenge. In this work, PANI is grafted onto epoxy functionalized phosphorylated poly (vinyl alcohol) (PPVA) with different side-chain configurations in order to improve compatibility and dispersion stability. These functionalized PPVA are synthesized using epichlorohydrin (ECIP) or γ-glycidyl methacrylate (GMA) as modifying agents, and respectively labeled as E-PPVA and G-PPVA. G-PPVA/PANI dispersion is stable even at a high PANI loading of 50%, while the maximum PANI loading for E-PPVA/PANI is only 30%. With the incorporation of G-PPVA/PANI into waterborne alkyd resins (AR), the coating resistance is increased by 7 orders of magnitude, and the corrosion inhibition efficiency is up to 99.9%. The coating with the incorporation of G-PPVA/PANI also demonstrates superior long-term corrosion resistance in comparison with that AR/E-PPVA/PANI nanocomposite coating. • PANI is grafted onto epoxy functionalized PPVA with different side-chain. • Compatibility and dispersion stability between PANI and PVA increased. • Improved the uniform distribution of PANI within the alkyd resin • The coating resistance is increased by 7 orders of magnitude. • The corrosion inhibition efficiency is up to 99.9%. [ABSTRACT FROM AUTHOR]