Improving the dispersion and integration of single-walled carbon nanotubes in epoxy composites through functionalization

Considerable improvement in the dispersion of purified single-walled carbon nanotubes (SWNTs) in an epoxy composite was obtained through functionalization of the SWNTs by using an optimized H2SO4/70% HNO3 acid treatment and subsequent fluorination. Epoxy composites containing 1 wt % nanotubes were processed by dissolving the functionalized SWNTs in dimethylformamide and mixing with the epoxy resin thereafter. The functionalized nanotubes were observed to be highly dispersed and well integrated in the epoxy composites. The enhancement of mechanical properties of the latter was indicated by a 30% increase in modulus and 18% increase in tensile strength. This work demonstrates the practical use of combining acid treatment and fluorination to achieve functionalization and unroping of SWNTs. The functionalized SWNTs can be integrated into epoxy composites through the formation of strong covalent bonds in the course of epoxy ring-opening esterification and curing chemical reactions.