Recent Advances in Poly(vinyl Alcohol)-Based Anti-Corrosion Coatings: Composition, Cross-Linking Strategies and Corrosion Protection Mechanisms

Poly(vinyl alcohol) (PVA) has been widely investigated as a matrix for anti-corrosion coatings because of its continuous film-forming ability, relatively low cost, and the versatility of its hydroxyl groups for chemical modification. However, its high affinity for water remains a major limitation for long-term corrosion protection. Consequently, recent research has increasingly focused on cross-linking, nanostructuring, and functional modification of PVA to improve its resistance to moisture and aggressive environments. This review critically examines recent advances in PVA-based anti-corrosion coatings by integrating coating composition, cross-linking chemistry, micro- and nanostructural features, and electrochemical corrosion-protection mechanisms. Particular attention is given to the effects of glutaraldehyde, boric acid, citric acid, epichlorohydrin, and other multifunctional cross-linkers on network structure, mechanical behavior, water resistance, and barrier properties. The roles of urea, glycerol, inorganic fillers, nanomaterials, corrosion inhibitors, and inhibitor-containing nanocontainers are also evaluated in relation to coating durability and corrosion-protection performance. In addition to describing reported approaches, the review critically compares the influence of substrate, PVA characteristics, cross-linking conditions, nanofiller loading, coating architecture, electrolyte, exposure duration, and electrochemical parameters on the reported performance. Particular emphasis is placed on the relationships between cross-linked network structure, nanofiller dispersion, interfacial adhesion, electrolyte transport, and electrochemical response. The review further considers active inhibition, self-healing strategies, and environmental aspects of PVA-based coatings, while identifying limitations related to moisture sensitivity, long-term durability, and inconsistent reporting of experimental parameters. By integrating composition, cross-linking chemistry, structure–property relationships, and electrochemical evidence, this review provides a critical framework for understanding and designing more durable and environmentally compatible PVA-based anti-corrosion coatings.