Polyimide/substituted polyaniline–copolymer–nanoclay composite thin films with high damping abilities

Polyimide (PI)/poly(N-ethyl aniline-co-aniline-2-sulfonic acid)–clay (SPNEAC) nanocomposite films containing water-soluble SPNEAC were successfully synthesized. Atomic force microscopy studies showed a homogeneous distribution of coated clay particles in the PI matrix. The particle sizes varied between about 50 nm and about 220 nm in height and 6–7 μm in length in the nanocomposite containing 5 wt % SPNEAC. Average surface roughnesses of 0.253 and 34.9 nm were obtained for neat PI and the 5 wt % SPNEAC–PI nanocomposite, respectively. Dynamic mechanical spectrometry was used to study the viscoelastic transitions and their temperatures. The dynamic mechanical spectrometry results show a decreasing glass-transition temperature of the nanocomposites with increasing SPNEAC weight fraction. The area under the α-transition peak, which is associated with damping and impact energy, increased with increasing SPNEAC weight fraction. The impact energy of the nanocomposites was estimated with a viscoelastic model. It increased with increasing SPNEAC weight fraction, and a maximum value of 84.9 mJ was obtained. The viscoelastic model was based on the area under the α-transition peak, rubbery plateau modulus, and sample volume. A 5 wt % addition of SPNEAC improved the impact energy of neat PI films by 300%. Scanning electron micrographs of the nanocomposite films showed a less compact cross-sectional morphology. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013