Enhancement of physical properties of electroactive polyimide nanocomposites by addition of graphene nanosheets

Electroactive polyimide (EPI) nanocomposites with amino-capped aniline trimer and 4 '-(4,4 '-isopropylidene-diphenoxy)bis(phthalic anhydride) as monomers, and functionalized with carboxyl-graphene nanosheets, were prepared by thermal imidization. The as-prepared electroactive polyimide/graphene nanocomposite (EPGN) materials were then characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. In situ monitoring of the redox behavior of the as-prepared EPGN materials was performed by cyclic voltammetry studies. The effects of material composition on the mechanical, thermal, thermal transport, dielectric and molecular barrier properties of EPGN membranes were investigated by dynamic mechanical analysis, TGA, DSC, the transient plane source technique, LCR meter and gas permeability analyzer, respectively. It should be noted that all the properties of the EPGN membranes were found to improve substantially over those of non-electroactive polyimide and EPI. For example, upon loading of 1 wt% graphene, EPGN membranes were found to have an increase of over 20%, 5%, 65% and 20% in mechanical strength, thermal stability, thermal conductivity and dielectric constant, respectively, and a reduction of over 20% in gas permeability. (c) 2013 Society of Chemical Industry