Multilayered intercalation of 1-octanol into Brodie graphite oxide

Abstract

Multilayered intercalation of 1-octanol into the structure of Brodie graphite oxide (B-GO) was studied as a function of temperature and pressure. Reversible phase transition with the addition/removal of one layer of 1-octanol was found at 265 K by means of X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). The same transition was observed at ambient temperature upon a pressure increase above 0.6 GPa. This transition was interpreted as an incongruent melting of the low temperature/high pressure B-GO intercalated structure with five layers of 1-octanol parallel to GO sheets (L-solvate), resulting in the formation of a four-layered structure that is stable under ambient conditions (A-solvate). Vacuum heating allows the removal of 1-octanol from the A-solvate layer by layer, while distinct sets of (00l) reflections are observed for three-, two-, and one-layered solvate phases. Step by step removal of the 1-octanol layers results in changes of distance between graphene oxide planes by ∼4.5 Å. This experiment proved that both L- and A-solvates are structures with layers of 1-octanol parallel to GO planes. Unusual intercalation with up to five distinct layers of 1-octanol is remarkably different from the behaviour of small alcohol molecules (methanol and ethanol), which intercalate B-GO structure with only one layer under ambient conditions and a maximum of two layers at lower temperatures or higher pressures. The data presented in this study make it possible to rule out a change in the orientation of alcohol molecules from parallel to perpendicular to the GO planes, as suggested in the 1960s to explain larger expansion of the GO lattice due to swelling with larger alcohols.

Swelling of graphene oxide membranes in alcohols: effects of molecule size and air ageing

“…[24][25][26] Simultaneous evaluation of multilayered GO lm thickness and amount of sorbed solvent can be performed using Neutron Reectivity (NR) methods. 15,27 Swelling of precursor graphite oxides in polar solvents has been studied in detail over the past 150 years, most typically in water, 21,28 alcohols [29][30][31][32] or amines. [33][34][35] The swelling of graphite oxides depends on the synthesis method, most notably for materials prepared by Brodie's and Hummers' oxidation routes.…”

Thermally reduced pillared GO with precisely defined slit pore size

“…The swelling of precursor PGO/TKAM in water and ethanol is somewhat weaker compared to graphite oxide 6,12,27,36 but anyway quite pronounced (Fig. 8).…”

“…30 BGO is a distinctly different material. 36 The swelling of BGO in methanol and ethanol at ambient temperature provides smaller inter-layer distance below 10Å (ref. 12) which is insuf-cient for penetration of relatively large TKAM molecules.…”

Graphite oxide swelling in molten sugar alcohols and their aqueous solutions

“…[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. [40,42,45] Moreover, selective intercalation of methanol from water/methanol mixtures was observed for BGO.…”

“…[45] Transitions between the phases with different number of intercalated solvent layers were found under variation of temperature or pressure. [40,42,45] Moreover, selective intercalation of methanol from water/methanol mixtures was observed for BGO. [46][47] In contrast, HGO shows no selectivity in sorption from binary mixtures, no phase transitions and absence of clearly distinct phases with certain amount of intercalated solvent.…”