Professor, Ingénierie des Matériaux Polymères, CNRS UMR 5223, Université de Lyon, France

Biography: Dr. Emmanuel Beyou obtained his PhD degree from the University of Bordeaux, France, in 1994, with research activities focusing on the synthesis of new fluorinated polysiloxanes exhibiting hydrophobic properties. Then, he carried out his postdoctoral research at the Charles Sadron Institute, Strasbourg, France, and he is presently Professor at the University of Lyon. His current research activities are located in the CNRS joint research unit "engineering of polymeric materials" and they are guided by the synthesis of both model macromolecular systems with controlled properties and nanocomposites. In particular, he has developed “graft-from” polymerization procedures onto fillers with different form factor in order to control their dispersion state in a polymer matrix. He is author of 55 papers in peer-reviewed international journals, 3 chapters of scientific books and serves as reviewer for numerous scientific journals and is expert for both national and international agencies.

Speech Title: Main interests in the Functionalization of Graphite Oxide Sheets with polymer chains
Aims: From an industrial application point of view, the most promising method for large scale production of graphene is based on the oxidation of graphite leading to graphite oxide (GO), which can subsequently be functionalized, followed by its reduction to restore electrical conductivity, if necessary.
Methods: First the treatment of GO with pentadecane, chitosan (CS) and polyisoprene (PI) through three main routes will be discussed as well as their characterization with the usual techniques (thermogravimetric analysis, etc…). Then, both the pntadecane- and PI-grafted graphene oxide sheets were compounded at various contents in a polyethylene and a polyisoprene matrix, respectively, the corresponding composites were studied through electrical, rheological and electron microscopy measurements. In addition, the CS-grafted GO nanohybrid material was doped with gold nanoparticles and its catalytic activity was studied.
Results: Rheological and electrical percolation thresholds were found between 10 and 15 wt% for pentadecane-functionalized graphene oxide composites while the graphite/PE composites at the same loading percentage did not reach any percolation threshold. Moreover, PI-based vulcanizates with a GO content of 15 phr (5 vol%) exhibited enhanced air barrier properties with an air permeability coefficient decrease of 35%. In addition, for Gold-based nanohybrids, it was found that this material exhibits a catalytic activity toward the reduction of nitrophenol to aminophenol.
Conclusions: The covalent functionalization of GO with polymer chains permits to ensure good dispersion of GO sheets in a polymer matrix ensuring improved electrical, mechanical and permeation properties of the corresponding composites.