Effect of sidewall modification in the determination of friction coefficient of vertically aligned carbon nanotube films using friction force microscopy

The significance of the sidewall surface of vertically aligned carbon nanotubes (VACNTs) and the effect of humidity in the determination of VACNT film friction coefficient have been investigated. VACNT films of 2 μm thick were sidewall-modified by means of CF4 and O2 plasma treatments, and verified for the functionalization of the sidewalls. They were then characterized for wettability properties, as well as friction coefficient using friction force microscopy at different humidity levels. It was found that humidity had insignificant effect on the friction coefficient, and sidewall friction formed a major component of the friction force experienced by the tip. Sidewall modifications resulted in friction coefficient changes of up to 50%.