Plasma Functionalization of Carbon Nanotubes for the Synthesis of Stable Aqueous Nanofluids and Poly(vinyl alcohol) Nanocomposites

Carbon nanotubes (CNTs) synthesized by direct thermal chemical vapor deposition growth from stainless steel mesh are surface functionalized via an Ar/O2/C2H6 capacitively coupled RF plasma discharge. The open and rigid network of CNTs allows for a high degree of the CNT surface to be treated. As a result, the aqueous nanofluids that are produced by removing the CNTs from the substrate are found to remain stable for extended periods of time (greater than six months). X-ray photoelectron spectroscopy analysis revealed that oxygen comprised approximately 21at.% of the functionalized CNT surface. Poly(vinyl alcohol)/CNT nanocomposites produced using the plasma functionalized CNTs are homogenous with excellent dispersion of the CNTs. Mechanically, the 0.75wt.-% functionalized-CNT nanocomposite show 54 and 60% increases in tensile strength and modulus, respectively, over the neat polymer. Little to no change is seen in the degree of crystallinity or the glass transition and melting point temperatures of the nanocomposites. Finally, water content is found to have a significant effect on the polymer and composite's tensile properties.