Graphene/Thermoplastic Polyurethane Nanocomposites

Graphene is atomically thin carbon sheets which have great potential as a reinforcement for polymers. Thermally exfoliated (Functionalized Graphene Sheets, FGS) and isocyanate-modified graphite oxide (iGO) were incorporated in thermoplastic polyurethane (TPU) via melt intercalation, solvent mixing and in-situ polymerization. Properties of the solvent mixed samples showed remarkable improvement. Conductivity percolation was achieved with only 0.5 wt% FGS and 3 wt% resulted in 10x increase in modulus and 80x reduction in nitrogen permeability. Transmission electron microscopy (TEM) and wide-angle X-ray scattering indicated that FGS is exfoliated while iGO forms mixed morphology of partial intercalation and exfoliation. TPU samples polymerized with FGS or GO exhibited reduced inter-domain hydrogen bonding. Average aspect ratios of graphitic additives determined by fitting properties with composite theories show good qualitative agreement with observation from TEM imaging and X-ray scattering.