Disclosed herein are graft polymers having a copolymer backbone and polycyclic aromatic hydrocarbon branches for use as a nanofiller dispersant and methods for making the same. Also disclosed are elastomeric nanocomposite compositions comprising a halobutyl rubber matrix, nanoparticles of graphite or grapheme, and the graft polymer. Such elastomeric nanocomposite compositions are suitable as tire innerliners or innertubes.