Vapor-Phase Functionalization of Vertically Aligned Carbon Nanotubes

Vertically aligned carbon nanotubes (CNTs) have important applications in biosensing owing to their excellent electronic properties and pre-defined ordered structure. Current research mainly focuses on functionalization of non-aligned nanotubes using solution-based protocols. Functionalization of aligned CNTs is still unexplored due to the difficulty of preserving the desirable alignment. We report a vapor-phase method to functionalize aligned CNTs with the nanotube alignment retained. The process involves flowing of functional monomer vapors around nanotubes and reaction of the monomer molecules to deposit ultra-thin nanocoatings around each individual nanotube. We demonstrated the functionalization of both multi-walled and singled-walled aligned carbon nanotubes using this vapor deposition method. A variety of surface chemistry, including hydrogel and epoxy chemistry, can be incorporated onto the nanotubes. We also demonstrated the control to covalently and non-covalently attach the functional layers to the nanotubes. Enzyme activity on the nanotubes is significantly improved as a result of the vapor-phase functionalization.