Multifunctional Smart Coatings: Materials Design, Processing Techniques and Structural Performance

Smart coatings are advanced functional materials designed to respond adaptively to environmental stimuli such as temperature, pH, light and mechanical stress. Unlike conventional coatings, they provide dynamic functionalities including self-healing, anti-microbial activity, self-cleaning and environmental responsiveness, making them essential for applications in aerospace, biomedicine, energy and electronics. Recent progress in multifunctional smart coatings is summarised in this review, with a focus on classification based on functional behaviour such as self-healing, stimuli-responsive, anti-microbial and conductive systems. The underlying mechanisms are discussed, including microencapsulation, dynamic covalent bonding, supramolecular interactions and responsive polymer networks. Fabrication techniques such as sol–gel processing, layer-by-layer assembly, electrochemical deposition and vapour deposition are evaluated in terms of structural control and performance optimisation. Industrial applications are highlighted and current challenges related to durability, scalability and environmental safety are identified. Future perspectives emphasise sustainable material design, multifunctional integration and digital connectivity for intelligent surface systems.