Salvio Riccardo, Krabbenborg Sven, Naber Wouter J M, Velders Aldrik H, Reinhoudt David N, van der Wiel Wilfred G
Supramolecular Chemistry and Technology Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Chemistry. 2009 Aug 17;15(33):8235-40. doi: 10.1002/chem.200900661.
The treatment of a suspension of graphite oxide (GO) with sodium azide leads to a material that, after reduction, features amino groups at the top and bottom of the sheets. These groups react through microcontact printing with an isothiocyanate monolayer on a silicon oxide substrate to form covalent bonds that strongly attach to the particles on the surface. With ultrasonication it is possible to obtain exfoliation of the sheets that are not covalently bound to the surface leaving single-layer platelets attached to the substrate. The azido derivative can be also used to functionalize the graphene oxide with long alkylic chains through a click chemistry approach. This functionalization results in the exfoliation of this material in dimethylformamide. The novel materials were fully characterized by different techniques including IR spectroscopy, thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM), X-Ray photoelectron spectroscopy (XPS), and solid state NMR spectroscopy. The material with amino groups, after the reduction step, is conductive with a resistivity only approximately seven times larger than that of unprocessed graphite. This implies that after reduction of the GO, the conjugated sp2 network is largely restored. We consider this to be an important step towards a chemical approach for forming conducting large-area platelet films of single-layer graphene.
用叠氮化钠处理氧化石墨（GO）悬浮液会得到一种材料，该材料在还原后，其薄片的顶部和底部具有氨基。这些基团通过微接触印刷与氧化硅衬底上的异硫氰酸酯单层发生反应，形成牢固附着在表面颗粒上的共价键。通过超声处理，可以使未与表面共价结合的薄片剥落，从而使单层薄片附着在衬底上。叠氮基衍生物还可用于通过点击化学方法用长烷基链对氧化石墨烯进行功能化。这种功能化导致该材料在二甲基甲酰胺中剥落。通过红外光谱、热重分析（TGA）、扫描和透射电子显微镜（SEM和TEM）、X射线光电子能谱（XPS）以及固态核磁共振光谱等不同技术对这些新型材料进行了全面表征。经过还原步骤后，带有氨基的材料具有导电性，其电阻率仅比未处理的石墨大约大七倍。这意味着在GO还原后，共轭的sp2网络在很大程度上得以恢复。我们认为这是迈向通过化学方法形成大面积单层石墨烯导电薄片薄膜的重要一步。
