Carbon nanotubes: From molecular to macroscopic sensors

The components that contribute to Raman spectral shifts of single-wall carb on nanotubes (SWNT's) embedded in polymer systems have been identified. The temperature dependence of the Raman shift can be separated into the temper ature dependence of the nanotubes, the cohesive energy density of the polym er, and the buildup of thermal strain. Discounting all components apart fro m the thermal strain from the Raman shift-temperature data, it is shown tha t the mechanical response of single-wall carbon nanotubes in tension and co mpression are identical. The stress-strain response of SWNT's can explain r ecent experimental data for carbon nanotube-composite systems.