Critical and comparative evaluation of waterborne polymer resin based coatings for corrosion protection

Corrosion remains a major challenge that compromises the durability, safety, and service life of metallic structures, resulting in substantial economic losses and environmental concerns worldwide. Although conventional solvent-based polymer coatings provide effective corrosion protection, their high volatile organic compound (VOC) emissions have accelerated the development of environmentally sustainable waterborne polymer coatings. This review critically evaluates recent advances in waterborne epoxy, acrylic, and polyurethane coatings by comparatively analysing their resin chemistry, synthesis strategies, curing behaviour, corrosion protection mechanisms, electrochemical performance, and industrial applicability. The available literature demonstrates that the corrosion protection performance of waterborne coatings is governed by the synergistic interactions between the polymer matrix, cross-linking characteristics, nanofiller dispersion, and functional additives. The incorporation of graphene oxide, polymer–clay nanocomposites, metal oxide nanoparticles, and environmentally benign corrosion inhibitors significantly enhances barrier properties, interfacial adhesion, and long-term corrosion resistance. However, challenges such as nanofiller agglomeration, moisture sensitivity, limited long-term field validation, and the lack of standardized corrosion testing protocols continue to hinder large-scale industrial implementation. By critically comparing the advantages, limitations, and recent developments of waterborne epoxy, acrylic, and polyurethane coating systems, this review identifies key knowledge gaps, discusses unresolved scientific and technological challenges, and outlines future research directions for the development of durable, high-performance, and sustainable anticorrosion coatings. The findings presented in this review provide a comprehensive scientific framework for advancing next-generation environmentally sustainable corrosion protection technologies and facilitating their broader industrial application.