Chemical Postdeposition Treatments To Improve the Adhesion of Carbon Nanotube Films on Plastic Substrates.

Abstract

The robust adhesion of single-walled carbon nanotubes (SWCNTs) to plastic substrates is a key issue toward their use in flexible electronic devices. In this work, semitransparent SWCNT films were prepared by spray-coating on two different plastic substrates, specifically poly(ethylene terephthalate) and poly(vinylidene fluoride). The deposited SWCNT films were treated by dipping in suitable solvents separately, namely, 53% nitric acid (HNO3) and N-methyl pyrrolidone. Direct evidence of SWCNT adhesion to the substrate was obtained by a peel-off test carried out with an adhesive tape. Moreover, these treatments caused enhanced film transparency and electrical conductivity. Electron microscopy images suggested that SWCNTs were embedded in the plastic substrates, forming a thin layer of conductive composite materials. Raman spectroscopy detected a certain level of doping in the SWCNTs after the chemical treatments, which particularly affected metallic nanotubes in the case of the HNO3 treatment. The microscopic adhesion and hardness of the SWCNT films were studied through a nanoscratch test. Overall, the efficiency of selected chemical postdeposition treatments for improving the SWCNT adhesion and the robustness of the resulting SWCNT films are demonstrated on flexible substrates of different chemical compositions.