Functional Polymer Nanocomposite Coatings for Naval and Maritime Applications: Advances in Protection, Durability, and Surface Engineering

Marine and naval materials are exposed to complex degradation resulting from the combined effects of chloride-induced corrosion, biofouling, mechanical wear, ultraviolet radiation, and microbiologically influenced corrosion. This review critically examines recent advances in protective coating technologies for improving the durability and sustainability of materials operating in aggressive marine environments. Attention is given to polymer-based and nanocomposite coatings, smart and self-healing systems, sustainable formulations, and advanced deposition and performance-assessment strategies. The reviewed literature shows a clear transition from conventional passive barrier coatings toward multifunctional systems that combine barrier protection with active corrosion inhibition, self-healing, antifouling behavior, and enhanced mechanical resistance. Nanostructured fillers can improve coating performance by restricting the transport of water, oxygen, and chloride ions, while inhibitor-loaded carriers and stimulus-responsive systems provide localized protection after coating damage. Sustainable polymers, bio-based additives, and environmentally compatible inhibitors are also emerging as alternatives to conventional formulations with greater environmental impact. However, long-term durability, scalability, reproducibility, and performance under real marine exposure remain major limitations to industrial implementation. Future progress therefore requires the development of multifunctional and environmentally compatible coating systems supported by standardized multifactor testing, long-term field validation, and scalable industrial processing.