Understanding silica aerogel-carbon nanotube composite structures by molecular simulation

Abstract

Silica aerogel-carbon nanotube composites are remarkable materials but with engineering principles poorly understood, particularly with regards to the structure of the silica aerogel at the interface with the carbon nanotubes (CNTs), and the physical phenomena behind it. This work provides valuable insights on this topic through classical molecular dynamics simulations. The effects on aggregation and adsorption on nanotubes caused by different types of silica primary particles, oxidation degree of the CNTs and solvent composition were explored. Silica monomers interact appreciably only with oxidized nanotubes via H-bonds with O-containing groups, whereas condensed primary particles adsorb almost completely to the surface due to siloxane-aromatic C van der Waals interactions. The adsorbed layer is highly structured owing to the preferential orientation of siloxane bonds tangentially to the CNT surface and formation of intralayer H-bonds.