W. Hung, Chi-Hui Tsou, M. Guzmán
Apr 25, 2014
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Chemistry of Materials
Abstract
Three diamine monomers (ethylenediamine, butylenediamine, and p-phenylenediamine) were selected for cross-linking graphene oxide (GO) to prepare composite graphene oxide-framework (GOF) membranes through filtration using a pressure-assisted self-assembly technique. The membranes were applied to separate an ethanol–water mixture by pervaporation. Unmodified GO comprised only hydrogen bonds and π–π interactions, but after cross-linking it with a diamine, attenuated total reflectance–Fourier transform infrared and X-ray photoelectron spectroscopy demonstrated that the diamine was chemically bonded both to GO and the membrane support. Moreover, GO hydrophilicity was substantially altered; water contact angle increased from 24.4° to 80.6° (from cross-linking with an aliphatic structure of diamine to cross-linking with an aromatic structure). Results of X-ray diffraction showed that d-spacing in GOF layers varied from 10.4 to 8.7 A. For GOFs presoaked in 90 wt % ethanol–water, covalent bonds between the layer a...