Improving the adhesion of carbon nanotubes to a substrate using microwave treatment

The effect of microwave (MW) treatment to improve the adhesion of carbon nanotubes (CNTs) to a Ni/Ti/Au/SiO2/Si substrate was examined. CNTs were synthesized at a low temperature (400 °C) by thermal chemical vapor deposition to avoid metal peeling. Results demonstrated that nearly 100% of MW-treated CNTs remained on the substrates even after sonication in a buffer solution. This was a significant improvement of adhesion compared to preparations not undergoing MW treatment, where almost no CNTs remained. Transmission electron microscopy of cross sections showed that before MW treatment, CNTs with Ni nanoparticles were located on the upper part of the Ti underlayer, whereas after MW treatment they were embedded in the Ti underlayer. Based on these results, a mechanism of adhesion improvement by MW treatment is proposed.