Viscoelasticity and high buckling stress of dense carbon nanotube brushes

We report on the mechanical behavior of a dense brush of small-diameter (1-3 nm) noncatalytic multiwall (2-4 walls) carbon nanotubes (CNTs), with similar to 10 times higher density than CNT brushes produced by other methods. Under compression with spherical indenters of different radii, these highly dense CNT brushes exhibit a higher modulus (similar to 17-20 GPa) and orders of magnitude higher resistance to buckling than vapor phase deposited CNT brushes or carbon walls. We also demonstrate the viscoelastic behavior, caused by the increased influence of the van der Waals' forces in these highly dense CNT brushes, showing their promise for energy-absorbing coatings. (C) 2009 Elsevier Ltd. All rights reserved.