Thin membranes of length purified single-wall carbon nanotubes (SWCNTs) are uniaxially compressed by depositing them on prestretched polymer substrates. Upon release of the strain, the topography, microstructure and conductivity of the films are characterized using a combination of optical/fluorescence microscopy, light scattering, force microscopy, electron microscopy and impedance spectroscopy. Above a critical surface mass density, films assembled from nanotubes of well-defined length (100 nm to 1000 nm) exhibit a strongly nonlinear mechanical response. The measured strain dependence suggests that the films are softening through an alignment of the SWCNTs normal to the direction of prestrain, which at small strains is also apparent as an anisotropic increase in sheet resistance along the same direction. At higher strains the film conductivities increase, which we attribute to a compression-induced restoration of conductive pathways.
Citation: Journal of Physical Chemistry C
Pub Type: Journals
nanotubes, flexible, electronics, polymers, wrinkling, modulus, conductivity, thin films