(491g) Directed Release of Chemical Energy In Single Walled Carbon Nanotube Films
Single Walled Carbon Nanotubes (SWNT) are promising materials as one-dimensional thermal conduits due to long phonon mean free paths along the axial length of the nanotube. Previous calculations predict that oxidation reactions conducted in an annular region encompassing the nanotube experience an increased reaction velocity in the direction of the nanotube length up to a factor of 10 to the bulk isotropic reaction(1). According to this model, vertically aligned carbon nanotube films should demonstrate even greater enhancement. In this work, we describe the synthesis, characterization and testing of a new class of 1-D energetic materials as chemical actuators and unique materials for propulsion. The porosity of aligned SWNT films was used to disperse mixtures of RDX and sodium azide by a wet impregnation method. SEM of the resulting film cross section shows annular coatings of the energetic crystals encompassing SWNT bundles in the film. While control samples without the carbon scaffold are unreactive, impregnated films demonstrate rapid energetic release that is orientated along the alignment direction of the film. High speed video microscopy is utilized to estimate reaction front velocities and specific impulse. Lastly, we discuss measurements of the temporal force evolution of such reactions. Applications to MEMS actuators, propulsion devices and synthetic platforms are discussed.
1. Joel T Abrahamson, Nitish Nair, Michael S Strano, Nanotechnology 19, (2008) 195702