Switchable Surfactant-Assisted Carbon Nanotube Coatings: Innovation through pH Shift

*Correspondence: Diego Cazorla-Amorós, Departamento de Química Inorgánica e Instituto Universitario de Materiales, University of Alicante, P.O. Box 99, San Vicente del Raspeig E-03080, Alicante, Spain e-mail: [email protected] The inner surface of fused-silica capillaries has been coated with a dense/homogeneous coating of commercial multi-wall carbon nanotubes (MWCNTs) using a stable ink as deposit precursor. Solubilization of the MWCNTs was achieved in water/ethanol/ dimethylformamide by the action of a surfactant, which can switch between a neutral or an ionic form depending on the pH of the medium, which thus becomes the driving force for the entire deposition process. Careful control of the experimental conditions has allowed us to selectively deposit CNTs on the inner surface of insulating silica capillaries by a simple, reproducible, and easily adaptable method.