Authors: M. Shaffer, R. Verdejo, M. Tran, A. Menner, A. Bismarck
Affilation: Imperial College London, United Kingdom
Pages: 191 - 193
Keywords: nanotubes, nanocomposites, polymers, functionalisation, surface modification
Although encouraging results have been obtained for nanotube-filled polymers, significant improvements over conventional fillers have proved elusive. A critical factor is the reliance on CVD-grown material, which is available in large quantity at reasonable purity, but defective and often entangled. However, a range of steps can be taken to improve the applicability of such materials, and to employ them in situations where they can provide a unique benefit. Commercially-available, CVD-grown, multi-walled carbon nanotubes can be disentangled by cutting; abrupt, repeated exposures to oxidising conditions in air is a clean, convenient and efficient means of producing material with open ends, moderate functionalisation, and enhanced solvent dispersibility; the surface character can easily be tuned to acidic or basic. These approaches could be deliberately integrated into conventional CVD processes, but also have implications for existing products. Matrix-filler interactions can be quantified by examining the contact angle of individual polymer droplets on single nanotubes, and correlated to the mechanical performance of corresponding macroscopic nanocomposites. Whilst optimising dispersion and wetting, there are immediate opportunities to exploit even imperfect nanotubes in fine structures where other reinforcements cannot be accommodated; examples include fibres, foams and the matrices of conventional fibre composites. In certain cases, the nanofiller can simultaneously aid processing and improve properties.