In-situ grafting of hyperbranched poly(ether ketone)s onto multiwalled carbon nanotubes via the A(3)+B-2 approach

Abstract

Trimesic acid and phenyl ether were in-situ polymerized as A3 and B2 monomers, respectively, in the presence of a fixed amount (10 wt %) of multiwalled carbon nanotube (MWNT) to afford hyperbranched poly(ether ketone)s (PEK's)/MWNT nanocomposites. The feed ratios of A3 and B2 monomers vary from 3:2 to 1:2 in the A3 + B2 polycondensations. The polymerization was carried out in a mildly acidic medium, i.e., poly-(phosphoric acid) or PPA, with an optimized amount of phosphorus pentoxide (P2O5) added. The overall evidence based on the data of elemental analysis (EA), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM) implicates that hyperbranched PEK's were attached to the surface of MWNT to form hyperbranched PEK-g-MWNT nanocomposites. Furthermore, MWNT remained structurally intact under the polymerization and workup conditions. Evidently driven by the molecular architecture of globular hyperbranched polymers, the morphology of the nanocomposites resembles "mushroom-like clusters on MWNT stalks". The hyperbranched PEK-g-MWNT nanocomposites were soluble in polar aprotic solvents stemming from numerous carboxylic acids on their surfaces. When some of samples were dispersed in 1 M LiOH aqueous solutions, they formed very stable suspensions. The resulting lithiated nanocomposites are being investigated in the applications such as ion conductivity and energy capacitance.