Preparation and properties of fluorine-containing colorless polyimide nanocomposite films with organo-modified montmorillonites for potential flexible substrate.

We prepared transparent polyimide (PI) and organo-modified montmorillonite (OMMT) nanocomposite films from the solution of poly(amic acid) and various amounts (0.5-2 wt%) of OMMT in N,N-dimethylacetamide (DMAc). The Poly(amic acid) was prepared from the reaction of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,2'-bis (trifluoromethyl)-4,4'-diamino phenyl (TFDB). Dodecylamine (C12-) and dodecyltriphenylphosphonium chloride (C12PPh-Cl-) were used as organic modifiers in OMMT. The PI/OMMT nanocomposite films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis transmission spectra, thermomechanical analysis (TMA), and rheometric dynamic analysis (RDA). As the OMMT contents is increased, PI/OMMT nanocomposites generally show better properties compared to pristine PI films, although the transparency of the PI/OMMT nanocomposite films is sacrificed slightly. However, it is concluded that these nanocomposite films are good candidates for potential flexible substrates.