Electronic and mechanical properties of single-walled carbon nanotubes interacting with epoxy: A DFT study

Abstract

Carbon nanotubes exhibit extremely high stiffness and strength, and are regarded as perfect reinforcing fibers for developing a new class of nanocomposites. The use of quantum mechanical calculations is more accurate than other atomistic methods for studying the interface and mechanical properties on the nanoscale for such materials. Ab initio calculations based on density functional theory (DFT) are employed to investigate the interaction properties of epoxy on typical zigzag and armchair single-walled carbon nanotubes (SWCNTs). The interaction energies for epoxy monomers with different orientations on SWCNTs are investigated. The results indicate that epoxy is weakly bound to the outer surface of the considered nanotubes and that the obtained interaction energy values are typical for physisorption. In addition, the influence of different defects (Stone–Wale, one- and two-atom vacancies) and functional groups (–NH2 and –OH) on the interaction properties between the epoxy and the respective SWCNTs has been investigated. Our results indicate that the interaction energy between the SWCNT and the epoxy decreased as the number of defects increased. In addition, the strongest interaction was observed for the SWCNT functionalized with the –OH group. Therefore, DFT calculations were performed to investigate the effect of the –OH functional group on the mechanical properties of SWCNTs interacting with epoxy.