Polymer / graphite oxide nanocomposites before and after thermal reduction

Nanocomposites of hyperbranched polymers with graphitic materials are investigated with respect to their structure, thermal properties as well as the dynamics of the polymer. Three generations of hyperbranched polyester polyols are mixed with graphite oxide, GO, and the favorable interactions between the polymers and the surfaces lead to intercalated structures. The thermal transitions of the confined chains are suppressed, whereas their dynamics show similarities and differences with the dynamics of the neat polymers. The three relaxation processes observed for the neat polymers are observed in the nanohybrids as well, however with different temperature dependencies. Thermal reduction of the graphite oxide in the presence of the polymer to produce reduced graphite oxide, rGO, reveals an increase of the reduction temperature accompanied by a decreased thermal stability of the polymer. The de-oxygenation of the graphite oxide leads to the destruction of the intercalated structure and to the dispersion of the rGO layers within the polymeric matrix because of the modification of the interactions between the polymer chains and the surfaces. A significant increase of the conductivity of the resulting nanocomposites, in comparison to both the polymers and the intercalated nanohybrids, indicates the formation of a percolated rGO network. Acknowledgements: This research has been financed by FORTH Synergy Grands-project PlaNet.