Spraying layer-by-layer assembly film based on the coordination bond of bioinspired polydopamine–FeIII

• Spraying layer-by-layer assembly has been used to construct superhydrophobic films.
• Bioinspired coordination bond of polydopamine and Fe3 + is employed.
• The surface of the multilayer films shows a hierarchical micro/nano-structures.

Spraying layer-by-layer (LbL) assembly technique has been developed for rapid and efficient fabrication of functional films. The spraying method generally requires relatively fast formation of stable interactions among the building components. In this study, inspired by nature, the fast and strong coordination bond between catechol groups (polydopamine, PDA) and metal ions (Fe3 +) was employed to fabricate (poly(ethylenimine)/PDA-coated carbon nanotubes) (PEI/CNTs@PDA) multilayer film. The coordination bond significantly enhanced the films' crosslinking during the spraying LbL procedures. Ellipsometry results confirmed the successful assembly of the [PEI/(CNTs@PDA + Fe3 +)] multilayer film. The hierarchical micro/nano-structures were observed on the multilayer surface. As a potential functionalization, the multilayer film was then coated with a low surface energy silane compound via thermal chemical vapor deposition method, leading to a superhydrophobic surface. By taking advantages of the specific rapid coordination bond of PDA and Fe3 +, this study provides an efficient and fast strategy to fabricate functional surfaces through spraying LbL assembly.