Investigation of molecular interactions between SWNT and polyethylene/polypropylene/polystyrene/polyaniline molecules

Single-walled nanotubes (SWNTs), which have a unique electronic structure, nanoscale diameter, high curvature, and extra-large surface area, are considered promising reinforcement materials for the next generation of high-performance structural and multifunctional composites. In the present study, force-field-based molecular dynamics simulations are performed to study the interaction between polymers and SWNTs. The "wrapping" of nanotubes by polymer chains was computed. The influence of temperature, nanotube radius, and chirality on polymer adhesion was investigated. Furthermore, the "filling" of nanotubes by polymer chains was examined. The results show that the interaction between the SWNT and the polymer is strongly influenced by the specific monomer structure such as aromatic rings, which affect polymers' affinities for SWNTs significantly. The attractive interaction between the simulated polymers and the SWNTs monotonically increases when the SWNT radius is increased. The temperature influence is neglectable for polyethylene (PE) and polypropylene (PP) but strong for polystyrene (PS) and polyaniline (PANI). Also, our simulations indicate that the adhesion energy between the SWNT and the polymer strongly depends on the chirality. For SWNTs with similar molecular weights, diameters, and lengths, the armchair nanotube may be the best nanotube type for reinforcement. The simulations of filling reveal that molecules of PE, PP, and PS can fill into a (10, 10) SWNT cavity due to the attractive van der Waals interactions. The possible extension of polymers into SWNT cavities can be used to structurally bridge the SWNTs and polymers to significantly improve the load transfer between them when SWNTs are used to produce nanocomposites.