Delamination of graphite oxide in a liquid upon cooling

Abstract

Graphite oxide (GO) in liquid acetonitrile undergoes a transition from an ordered phase around ambient temperatures to a gel-like disordered phase at temperatures below 260K, as demonstrated by in-situ x-ray diffraction. The stacking order of GO layers is restored below the freezing point of acetonitrile (199K). The reversible swelling transition between a stacked crystalline phase and an amorphous delaminated state observed upon cooling provides an unusual example of increased structural disorder at lower temperatures. The formation of the gel-like phase is attributed to the thermo-responsive conformational change of individual GO flakes induced by stronger solvation. Scanning force microscopy demonstrates that GO flakes deposited onto a solid substrate from acetonitrile dispersions at a temperature below 260K exhibit corrugations and wrinkling not observed for the flakes deposited at ambient temperature. The thermo-responsive transition between delaminated and stacked phases reported here can be used for sonication-free dispersion of graphene oxide, micro-container applications, or the preparation of new composite materials.

Sorption of polar organic solvents and water by graphite oxide: Thermodynamic approach

“…However, such anomalous behavior is poorly understood and lack theoretical explanation. For B-GO the abrupt changes of the inter-layer distance were observed in the systems with CH 3 OH, C 2 H 5 OH, DMF and CH 3 CN, suggesting transitions between two solvate phase to occur upon temperature variations [26,27].…”

Graphite oxide swelling in molten sugar alcohols and their aqueous solutions

“…Note that strong change in composition of GO solvates was observed in our earlier studies around the point of solvent freezing/melting for BGO/water system [55] and not observed for BGO in methanol and several other solvents. [44,61] A second heating cycle with the same sample was then performed to verify stability and possible phase transformations at higher temperatures. The same phase of BGO/xylitol and BGO/sorbitol was observed in this experiment up to the highest temperature point of 480 K which is just below the temperature of explosive exfoliation of BGO.…”

“…Detailed characterization of these materials using XRD, FTIR, TGA and some other methods were presented in our previous publications. [30,40,44,48,56] The ref [56] provides characterization of the same materials as those which are used here for study of sugar alcohol intercalation. XRD data were recorded using in house diffractometers Siemens D5000…”

“…Distinctly different phases which correspond to the structures intercalated with one and two layers of solvent were reported in our earlier studies for BGO in liquid methanol, [41] ethanol, [42] DMF, [42] acetone, [43] acetonitrile, [44] and several others. [44] Multilayered intercalation of octanol was reported in our most recent study.…”

“…[44] Multilayered intercalation of octanol was reported in our most recent study. [45] Transitions between the phases with different number of intercalated solvent layers were found under variation of temperature or pressure.…”