van der Waals interaction between carbon nanotubes and on non-covalent functionalization of PEEK is investigated. The Lennard-Jones potential function and the continuous assumption are employed to determine the total interaction energy of the system. In contrast to using a computational technique to find the energy behavior, our aim here is to obtain an analytical expression as a function of the nanotube radius and the atomic composition of the polymer. In particular, we investigate the interaction energy between a parallel pair of coated and uncoated nanotubes to demonstrate an alignment of carbon nanotubes in the polymer matrix. This is an example of a theoretical observation that might be used to determine the energy behavior of other polymer-based composites.
We find that bare carbon nanotubes give the strongest binding energy as compared to functionalized CNTs. The equilibrium distance between the closest surfaces of the two nanotubes is obtained as 0.32 nm. Our results suggest that this value does not depend on the tube radius nor on the number of carbon nanotube walls.
Double- and multi-walled CNTs have a larger interaction energy than single-walled CNTs which makes them harder to disperse in a polymer matrix. Clearly non-covalent functionalization reduces the tube interaction energy and favours dispersion of the CNTs in the polymer matrix.
Ref: Duangkamon Baowan et al 2019 J. Phys. Commun. 3 035018