Role of metal ion promoters in carbon nanotubes functionalization by polydopamine in the perspective of electroplated copper–carbon composites

Abstract

The present study investigates the sinergetic role of pH and metal ions promoters (Cu²⁺ and Ni²⁺) in the tailoring of polydopamine (PDA) functionalization of carbon nanotubes (CNTs) with the ultimate goal of integration and control of copper matrix composites. We hereby demonstrate that mildly alkaline conditions combined with the presence of redox-active metal ions significantly enhance the yield of PDA coating on CNTs surface, by promoting dopamine polymerization via metal-assisted autoxidation and chelation mechanisms. The use of a catecholamine (PDA) coating and incorporation of metal promoters like copper and nickel enabled stability of the spraying solution. The effects of the CNTs surface modifications on the polymerization yield and electrical properties were evaluated. Although PDA reduces the functionalized CNTs conductivity due to its insulating nature, its role as a versatile interfacial layer is amplified in the presence of metal ions, which facilitate denser and more homogeneous polymer deposition. These findings reveal how surface modification enhances copper–carbon interfaces in CNT-based metal matrix composites, improving composite design and performance for lightweight applications requiring high current resistance, such as lightning strike protection in aircraft.