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Multifunctional elastomer nanocomposites with functionalized graphene single sheets

We demonstrate the use of functionalized graphene sheets (FGSs) as multifunctional nanofillers to improve me- chanical properties, lower gas permeability, and impart electri- cal conductivity for several distinct elastomers. FGS consists mainly of single sheets of crumbled graphene containing oxy- gen functional groups and is produced by the thermal exfolia- tion of oxidized graphite (GO). The present investigation includes composites of FGS and three elastomers: natural rub- ber (NR), styrene-butadiene rubber, and polydimethylsiloxane (PDMS). All of these elastomers show similar and significant improvements in mechanical properties with FGS, indicating that the mechanism of property improvement is inherent to the FGS and not simply a function of chemical crosslinking. The decrease in gas permeability is attributed to the high as- pect ratio of the FGS sheets. This creates a tortuous path mechanism of gas diffusion; fitting the permeability data to the Nielsen model yields an aspect ratio of � 1000 for the FGS. Electrical conductivity is demonstrated at FGS loadings as low as 0.08% in PDMS and reaches 0.3 S/m at 4 wt % loading in NR. This combination of functionalities imparted by FGS is shown to result from its high aspect ratio and carbon-based structure. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 910-916, 2012