Investigation of aromatic/aliphatic polyimides as dispersants for single wall carbon nanotubes

Novel aromatic/aliphatic polyimides were prepared from 2,7-diamino-9,9'-dioctylfluorene (AFDA) and aromatic dianhydrides. Upon investigating the effectiveness of these polyimides for debundling single wall carbon nanotubes (SWNTs) in solution, three were discovered to aid in the dispersion of SWNTs in N,N-dimethylacetamide (DMAc). Two of these polyimides, one from 3,3',4,4'-oxydiphthalic anhydride (ODPA) and one from symmetric 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), were used to prepare nanocomposites. Homogeneous polyimide/SWNT suspensions from both polymers were used in the preparation of films and fibers containing up to 1 wt % SWNTs. The samples were thermally treated to remove residual solvent, and the films were characterized for SWNT dispersion by optical and high-resolution scanning electron microscopy (HRSEM). Electrical and mechanical properties of the films were also determined. Electrospun fibers were examined by HRSEM to characterize SWNT alignment and orientation.