Epoxide Exfoliants

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Science  18 Apr 2008:
Vol. 320, Issue 5874, pp. 291
DOI: 10.1126/science.320.5874.291a

The graphite form of carbon consists of strongly bonded two-dimensional sheets stacked relatively loosely on top of each other. One approach for separating graphite into these individual graphene sheets or multilayers—a morphology with broadly useful emerging electronic properties—involves preliminary oxidization. Solid-state nuclear magnetic resonance studies suggested that the major oxidation product is an epoxide, similar to the product formed upon oxidizing single-walled carbon nanotubes. Chattopadhyay et al. have obtained Raman spectral evidence for epoxide formation on graphite, and could furthermore quantify the extent of the reaction by methyltri-oxorhenium-catalyzed transfer of the oxygen atoms to triphenylphosphine, a reaction pathway specific to epoxides. They also imaged functionalization of individual flakes using high-resolution transmission electron microscopy and scanning tunneling microscopy. The reduced and oxidized forms showed similar basal plane roughness, which suggests that epoxidation occurs mainly at edge sites. — PDS

J. Am. Chem. Soc. 130, 10.1021/ja711063f (2008).

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