title: 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 temperature to a gel-like disordered phase at temperatures below 260 K, as demonstrated by in situ X-ray diffraction. The stacking order of GO layers is restored below the freezing point of acetonitrile (199 K). 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 260 K exhibit corrugations and wrinkling which are not observed for the flakes deposited at ambient temperature. The thermo-responsive transition between the 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.
authors.affiliation: Department of Physics, Umeå University, Umeå, SE-90187, Sweden. alexandr.talyzin@umu.se.
authors.forename: Alexandr V
authors.initials: AV
authors.lastname: Talyzin
authors.forename: Alexey
authors.initials: A
authors.lastname: Klechikov
authors.forename: Mikhail
authors.initials: M
authors.lastname: Korobov
authors.forename: Anastasiya T
authors.initials: AT
authors.lastname: Rebrikova
authors.forename: Nataliya V
authors.initials: NV
authors.lastname: Avramenko
authors.forename: M Fardin
authors.initials: MF
authors.lastname: Gholami
authors.forename: Nikolai
authors.initials: N
authors.lastname: Severin
authors.forename: Jürgen P
authors.initials: JP
authors.lastname: Rabe