Thermal conductivity and morphology of silver-filled multiwalled carbon nanotubes/polyimide nanocomposite films

A facile methodology has been developed to synthesize silver-filled multiwalled carbon nanotubes (S-MWNTs)-polyimide (PI) nanocomposites with high thermal conductivity for applications in flexible printed circuits or buried film capacitors, requiring efficient heat dissipation. MWNTs functioned as modules to facilitate the distribution of Ag particles within PI matrix. The intercalation of Ag within MWNTs was performed using capillary action upon mixing AgNO3 solution with PI precursor and followed by calcinations to reduce the ionic silver to Ag. The existence of Ag in the PI nanocomposites was observed from transmission electron microscope images and verified with the energy-dispersive X-ray spectrometer. Homogeneous dispersion of SMWNTs in PI matrix and strong interaction between S-MWNTs and PI were also suggested by SEM cross-section images. The thermal conductivity of S-MWNT/PI nanocomposite was a function of the content of S-MWNTs in PI matrix. The PI nanocomposite containing 1.5 wt % of S-MWNTs (S-MWNT/PI-1.5) exhibited the highest thermal conductivity, 0.37 W/mK. A decrease in thermal conductivity was observed while the surface roughness of the nanocomposite was higher than 1 mu m owing to the high content of S-MWNT in PI. In addition, the modified MWNTs improved flexibility of the PI matrix. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012