Self-Healing Polymer-Based Coatings: Mechanisms and Applications Across Protective and Biofunctional Interfaces

Self-healing polymer-based coatings have emerged as a new generation of adaptive protective materials capable of restoring their structure and function after damage. This review provides a comprehensive analysis of current strategies enabling autonomous or externally triggered repair in polymeric films, including encapsulation, reversible chemistry, and microvascular network formation. Emphasis is placed on polymer-inorganic hybrid composites and vitrimeric systems, which integrate barrier protection with stimuli-responsive healing and recyclability. Comparative performance across different matrices-epoxy, polyurethane, silicone, and polyimine-is discussed in relation to corrosion protection and biomedical interfaces. The review also highlights how dynamic covalent and supramolecular interactions in hydrogels enable self-repair under physiological conditions. Recent advances demonstrate that tailoring interfacial compatibility, healing kinetics, and trigger specificity can achieve repeatable, multi-cycle recovery of both mechanical integrity and functional performance. A representative selection of published patents is also shown to illustrate recent technological advancements in the field. Finally, key challenges are identified in standardizing evaluation protocols, ensuring long-term stability, and scaling sustainable manufacturing. Collectively, these developments illustrate the growing maturity of self-healing polymer coatings as multifunctional materials bridging engineering, environmental, and biomedical applications.