Grafting of Polyimide onto Chemically-Functionalized Graphene Nanosheets for Mechanically-Strong Barrier Membranes

A series of polyimide (PI) nanocomposite films with different loadings of aminophenyl functionalized graphene nanosheets (AP-rGO) was fabricated by in situ polymerization. AP-rGO, a multifunctional carbon nanofiller that can induce covalent bonding between graphene nanosheets and the PI matrix, was obtained through the combination of chemical reduction and surface modification. In addition, phenyl functionalized graphene nanosheets (P-rGO) were prepared by phenylhydrazine for reference nanocomposite films. Because of homogeneous dispersion of AP-rGO and the strong interfacial interaction between AP-rGO and the PI matrix, the resulting nanocomposite films that contained AP-rGO exhibited reinforcement effects of mechanical properties and oxygen barrier properties that were even better than those of pure PI and the reference nanocomposite films. In comparison to the tensile strength and tensile modules of pure PI, the composite films that contained AP-rGO with 3 wt % loading were increased by about 106% (262 MPa) and 52% (9.4 GPa), respectively. Furthermore, the oxygen permeabilities of the composites with 5 wt % filler content were significantly decreased, i.e., they were more than 99% less than the oxygen permeability of pure PI.