Rise of polycatecholamine ultrathin films: From synthesis to smart applications

Abstract Ultrathin polymeric films are fundamental for modern technologies, with applications spanning from protective coatings, membranes, to electronic interfaces. The need to optimize the synthesis and functionalization of nanometer-thick films fuels ongoing scientific and industrial innovation. Among emerging polymeric materials, polycatecholamines have attracted increasing interest as versatile two-dimensional (2D) ultrathin coatings, owing to their distinctive chemical structure and strong adhesion properties, qualities that have earned them the designation of “universal coatings.” This review highlights the molecular architecture of catecholamine-derived polymeric networks and evaluates key synthesis and functionalization strategies for ultrathin coating and free-standing film fabrication. Methods such as layer-by-layer assembly, solution-based deposition, and surface-initiated polymerization are critically assessed. We further examine the application potential of these coatings in diverse areas, including membrane technology, catalytic support frameworks, biosensing, and soft robotics. Recent advances are presented alongside a discussion of current limitations, particularly regarding their stability and scalability. Finally, we outline future directions for research and development in nanocoating technologies, emphasizing the role of functional nanomaterial design and interdisciplinary applications.