Single-wall carbon nanotube polymer composites: Investigating their percolative behavior and physical performance

In this work, an approach to enhance the electroactive response of polymers is pursued. Single-wall carbon nanotubes (SWNT) nanoinclusions are dispersed in a piezoelectric polyimide. A qualitative assessment of dispersion is done using optical microscopy and high resolution scanning electron microscopy. Key requirements for the resulting nanocomposites are flexibility, and thermal and chemical stability. Electrical and dielectric properties of the SWNT-reinforced polyimide composites are investigated as a function of SWNT concentration. AC and DC conductivities are measured. The experimental dielectric constant was found to obey a percolation-like power law with a relatively low percolation threshold. It is found that addition of the SWNT in the polyimide composites facilitates poling and results in an increase of the piezoelectric properties of the composites. Furthermore, at higher SWNT concentration, a bending strain is observed at relatively low electric fields, indicating the potential of using these composites actuators. Current investigations illustrate the effects of SWNTs on dielectric, piezoelectric and electroactive properties. Further work is ongoing to assess the effect SWNTs on the mechanical and thermal properties of the polyimide matrix.