Polymer-Functionalized Carbon Nanotubes Via Supercritical Carbon Dioxide Processing

The incorporation of carbon nanotubes (CNT) into a polymer can enhance the polymer's mechanical, thermal, and electrical properties. To aid in this effort, CNTs can be functionalized in order to increase their compatibility with the host polymer. The increase in compatibility serves to ensure a higher level of CNT dispersion and property transfer from the CNTs to the polymer matrix. The most commonly used method of nanotube functionalization is wasteful and environmentally unfriendly since it requires large amounts of toxic solvents. A solvent-free route to functionalization uses supercritical carbon dioxide as the processing medium. Multi-walled carbon nanotubes (MWCNTs) were processed with monomer and initiator in supercritical carbon dioxide to determine if MWCNTs could be functionalized with poly(methyl methacrylate) (PMMA) at the specified conditions. Grafting of PMMA to the walls of the MWCNTs was confirmed by Fourier transform infrared (FTIR) analysis.