Multiwalled carbon nanotubes and nanofibers grafted with polyetherketones in mild and viscous polymeric acid

Direct covalent attachment of amorphous and semicrystalline polyetherketones onto the surface of either an as-received multi-walled carbon nanotube (MWNT) or a vapor-grown carbon nanofiber (VGCNF) in polyphosphoric acid (PPA) with optimized P₂O₅ content resulted in uniform grafting of polyetherketones to these carbon nanoscale materials. Soxhlet extraction experiment, the spectra from FT-IR spectroscopy and the clear images from high-resolution transmission electron microscopy showed that the covalent attachment is effective in uniformly coating the PEK grafts on the surfaces of both MWNT and VGCNF. Additionally, a drastic increase in solution viscosity due to the formation of giant molecules was monitored during polymerization. As such, the resulting nanocomposites were easily fabricated via a simple compression molding technique. The alignment possibility of MWNT and VGCNF grafted with semicrystalline PEK in these thermoplastic nanocomposites via solution fiber spinning was also demonstrated.