Polyimide nanocomposites with novel functionalized-graphene sheet: thermal property, morphology, gas permeation, and conductivity

Abstract

4-Amino-N-hexadecylbenzamide-graphene sheets (AHB-GSs), used in the preparation of polyimide (PI) nanocomposite films, were synthesized by mixing a dispersion of graphite oxide with a solution of the ammonium salt of AHB. The atomic force microscopy image of the AHB-GSs on mica and a profile plot revealed the average sheet thickness to be similar to 3.21 nm. PI films were prepared by reacting 4,4'-biphthalic anhydride and bis(4-aminophenyl) sulfide. PI nanocomposite films containing different amounts of AHB-GS (0-10 wt%) were compared for their morphologies, thermal properties, gas permeation, and electrical and thermal conductivities. The graphenes, for the most part, were well dispersed in the polymer matrix despite some agglomeration. However, micrometer-scale particles were not detected. The average thickness of the particles was less than 10 nm, as revealed from the transmission electron microscope images. Only a small amount of AHB-GS was required to improve the coefficient of thermal expansion, gas permeation, and electrical and thermal conductivities. In contrast, the glass transition temperature and initial decomposition temperature of the PI hybrid films continued to decrease with increasing AHB-GS content up to 10 wt%. Copyright (C) 2015 John Wiley & Sons, Ltd.