Microwave-Assisted Synthesis and Characterization of Polyimide/Functionalized MWCNT Nanocomposites Containing Quinolyl Moiety

Polyimide-MWCNT nanocomposites were prepared by the reaction of a heterocyclic diamine monomer of bis(4-amino-3,5-dimethylphenyl)-2-chloro-3-quinolylmethane (BACQM), pyromellitic dianhydride (PMDA) with unmodified MWCNT (MWCNT), acid-functionalized MWCNT (acid-MWCNT) or amine-functionalized MWCNT (amine-MWCNT) using microwave irradiation as well as by the conventional method. The structure of the monomer was confirmed by FTIR, H-1-NMR, and C-13-NMR spectral techniques. The glass transition temperature (T-g) of the MWCNTs/polyimide nanocomposite was found to be higher than that of the unfilled polyimide system. The T-g's of both systems were higher when prepared with the microwave method than the conventional synthesis. The T-g's of the nanocomposites using acid and amine functionalized MWCNTs are greater than 300 degrees C, in both methods. This is attributed to the presence of hydrogen bond and strong covalent bond in both the acid-MWCNT/polyimide and amine-MWCNT/polyimide systems. The morphological studies of the nanocomposites synthesized using microwave irradiation show that a distinct MWCNT nanofibrillar network is formed in the matrix when MWCNT or acid-MWCNT is used. A homogeneous morphology, without distinct nanotube domains is seen when the amine-MWCNT is covalently linked to the polymer. (C) 2015 Society of Plastics Engineers