Study of the coating of SWCNT Buckypaper as an approach to develop CNT cables for electrical applications

Abstract

The objective of this research is to propose the best coating, out of 4 materials, for CNT wires in electrical applications, using the appropriate methodologies to study the surface phenomena between each coating and the carbon nanotubes. It was decided to use CNT film (Buckypaper), as a surrogate for carbon nanotube (CNT) cable. The Buckypaper (BP) showed similar porosity and surface structure to that present in CNT fibers. It also has the advantage of being easier to make at a laboratory scale. In this study, it was prepared by filtering a sonicated solution of single-walled carbon nanotubes and N,N-Dimethylformamide, through a polytetrafluoroethylene (PTFE) membrane of 0.45 µm pore size. The BP surface features were observed with Scanning Electron Microscopy, their chemical composition determined by X-ray Photoelectron Spectroscopy, their imperfections, and purity measured by Raman Spectroscopy and the porosity % and pore distribution obtained by Nitrogen Physisorption. All these measurements were considered as important on the wettability and adhesion of the coating on the BP. The surface free energy of the BP was obtained by first measuring the contact angles, and then applying the Owens-Wendt method. The surface tension of the coatings was calculated with the pendant drop method. The data was used to find the adhesion and wettability parameters. Afterward, the electrical conductivity of each coated Buckypaper was measured to decide which coating-BP system showed the best electrical conductivity performance.