Real-time neutron-scattering studies of molecular intercalation in Graphite Oxide

Resumen del trabajo presentado a la VI European Conference on Neutron Scaterring, celebrada en Zaragoza (España) del 30 de agosto al 4 de septiembre de 2015.Graphite Oxide (GO) has gained renewed interest for separation technologies or gas storage. The pillaring of GO via molecular intercalation provides a route to prepare porous materials with tunable pore size. Guest-host interactiones in GO can involve hydrogen bonding (HB), as in the case of alcohols. As expected for HB interactions, intercalation is reversible to a high degree. In addition, alcohols display a particulary rich phenomenology. For example, GO immersed in methanol and ethanol undegoes structural expansion upon cooling. By making recourse of the unique capabilities of the NIMROD diffractometer at the ISIS facility, we have stuided in real time the intercalation of liquid 1-Propanol (1-Pr) into a Brodie-type GO. NIMROD is a pulsed-neutron diffractometer that spans a very wide range of momentum transfers (0.02 > Q > 100 A-1) with an exceptionally high counting rate. Such a wide Q-range is ideally suited to explore mesoscopic length scales involved in molecular intercalation (~1 nm) and also provides robust estimates of chemical stoichiometry. Using a paracrystalline model, we have developed practical formulae to perform a quantitative analysis of staking disorder in layered materials. Such a quantitative assessment has revealed an unexpectedly rich phenomenology associated with the intercalation of liquid 1-Pr our GO substrate. In particular, 1-Pr intercalation leads to the formation of a monolayer structure with a much-improved stacking order than that of the pristine GO, and this intercalated phase remains mobile down to 130 K. heating up slowly from below 130 K, we observe and ordering transition to a thermally stable structure at ~200 K. This transition is also observed via dielectric spectroscopy. Further, the stabilized intercalated material allows for the reversible intercalation of a second 1 - Pr layer. this new nanostructure is stable enough to undergo a harsh drying process (in vacuo heating) without structural changes. The final 'dry' nanostructure is characterised by a much-improved stacking order relayive to prisine GO. Finally, we have also observed a strong isotopic effect with fully deuterated 1-pr. this intercalant undergoes a vastly different absorption kinetics relative to its hydrogenated 1-Pr. this intercalant undergoes a vastly different absorption kinetics relative to its hydrogenated counterpart. After heating in vacuo, enabling a further structural analysis of this novel composite material.Peer Reviewe