Preparation of a Homologous Series of Tetraalkylammonium Graphite Intercalation Compounds

Graphite intercalation compounds (GICs) of a series of symmetric or asymmetric tetraalkylammonium (TAA) intercalates are obtained from stage-1 [Na(en)(1.0)]C-15 via cation exchange. The prepared dull-black TAA-GICs contain either flattened monolayer or bilayer galleries, with significant cointercalation of the dimethylsulfoxide (DMSO) solvent in the bilayer galleries. The TAA-GIC products obtained are characterized by X-ray diffraction and related structural modeling, compositional analyses, and Raman spectroscopy. [(C4H9)(4)N]C-43 is obtained as a pure stage-1 GIC with the flattened monolayer structure. The larger symmetric TAA cations, (C6H13)(4)N, (C7H15)(4)N, (C8H17)(4)N, and the asymmetric TAA cations, (C12H25)(CH3)(3)N, (C18H37)(CH3)(3)N, (C18H37)(2)(CH3)(2)N, all form pure stage-1 GICs with flattened bilayer conformations. Thermogravimetric analyses combined with mass spectrometry and elemental analyses indicate the presence of similar to 1-2 DMSO cointercalates per bilayer cation. The intercalate layers in these TAA-GICs have expansions along the stacking direction of similar to 0.40 nm. Raman data confirm the low graphene sheet charge densities in the obtained TAA-GICs.