Ionosilica ionogels have been lately introduced as emerging all-ionic designer materials. They consist of an ionic liquid (IL) guest trapped within a solid ionosilica support host. In this work, we investigate the influence of the (i) ionosilica nature and (ii) the ionosilica/IL ratio on the mobility of the confined IL. We report the elaboration of various ionosilica ionogels via a nonhydrolytic sol-gel process, using namely tris(3-(trimethoxysilyl)propyl)amine (TTA), Methyl-tris(3-(trimethoxysilyl)propyl)ammonium iodide (MTTA) and tetrakis(3-(trimethoxysilyl)-propyl)ammonium iodide (TKTA) as ionosilica precursors, with the IL butyl-methyl imidazolium bis-triflimide ([BMIM] TFSI). Various ionogels were prepared from different ratios between the ionosilica host and the IL guest. The host/guest interactions i.e. the change in the conformational contribution of the IL counter-anion were explored by means of Raman spectroscopy. In addition, the transport properties of the confined species were probed via spin echo solid-state NMR experiments and Complex Impedance Spectroscopy (CIS) measurements. Raman experiments revealed different conformational equilibrium for the TFSI anion in the various ionosilica ionogels, with an increase in the cisoid form compared to the bulk IL due to confinement effects. The TFSI anion seems to experience different degree of confinement and thus different interactions with the ionosilica scaffold as a function of the investigated parameters. Concomitantly, the 1H spin echo NMR and CIS measurements revealed a significantly higher ionic mobility in the materials synthesized in the presence of the tris-trialkoxysilylated ammonium precursor compared to the one synthesized in the presence of tetra-trialkoxysilylated ammonium precursor. These results may reflect stronger host-guest interactions in the latter case related to the higher degree of reticulation of the network. All these techniques give concordant results and highlight an effect of the chemical constitution of the ionosilica scaffold and the amount of confined IL on its dynamics within the network.

This work explores a contactless resistivity measurement method dedicated to the study of quantum phenomena. The method belongs to the category of RadioFrequency (RF) eddy currents and is based on a gradiometric inductive coil.

Ionosilica ionogels, i.e. composites consisting of an ionic liquid (IL) guest confined in an ionosilica host matrix, were synthesized via a non-hydrolytic sol–gel procedure from a tris-trialcoxysilylated amine precursor using the IL [BMIM]NTf2 as solvent. Various ionosilica ionogels were prepared starting from variable volumes of IL in the presence of formic acid. The resulting brittle and nearly colourless monoliths are composed of different amounts of IL guests confined in an ionosilica host as evidenced via thermogravimetric analysis, FT-IR, and 13C CP-MAS solid-state NMR spectroscopy. In the following, we focused on confinement effects between the ionic host and guest. Special host–guest interactions between the IL guest and the ionosilica host were evidenced by 1H solid-state NMR, Raman spectroscopy, and broadband dielectric spectroscopy (BDS) measurements. The three techniques indicate a strongly reduced ion mobility in the ionosilica ionogel composites containing small volume fractions of confined IL, compared to conventional silica-based ionogels. We conclude that the ionic ionosilica host stabilizes an IL layer on the host surface; this then results in a strongly reduced ion mobility compared to conventional silica hosts. The ion mobility progressively increases for systems containing higher volume fractions of IL and finally reaches the values observed in conventional silica based ionogels. These results therefore point towards strong interactions and confinement effects between the ionic host and the ionic guest on the ionosilica surface. Furthermore, this approach allows confining high volume fractions of IL into self-standing monoliths while preserving high ionic conductivity. These effects may be of interest in domains where IL phases must be anchored on solid supports to avoid leaching or IL spilling, e.g., in catalysis, in gas separation/sequestration devices or for the elaboration of solid electrolytes for (lithium-ion) batteries and supercapacitors

La recherche présentée dans cette communication correspond à la première phase d’une recherche-formation qui s’intéresse aux outils développés et utilisés dans la formation en sciences des enseignants du premier degré. Nous présentons ici les résultats de la phase exploratoire de cette recherche, dans laquelle nous avons interrogé les usages d’un cahier de sciences par deux étudiantes. Les résultats montrent que l’outil a été perçu comme utile principalement en ce qui concerne les apprentissages en lien avec l’enseignement des sciences mais sans être perçu comme un outil potentiel pour les pratiques et de fait qu’il n’a très peu été utilisé dans les pratiques.

The so-called buffer layer (BL) is a carbon rich reconstructed layer formed during SiC (0001) sublimation.The covalent bonds between some carbon atoms in this layer and underlying silicon atoms makes itdifferent from epitaxial graphene. We report a systematical and statistical investigation of the BLsignature and its coupling with epitaxial graphene by Raman spectroscopy. Three different BLs arestudied: bare buffer layer obtained by direct growth (BL0), interfacial buffer layer between graphene andSiC (c-BL1) and the interfacial buffer layer without graphene above (u-BL1). To obtain the latter, wedevelop a mechanical exfoliation of graphene by removing an epoxy-based resin or nickel layer. The BLsare ordered-like on the whole BL growth temperature range. BL0 Raman signature may vary from sampleto sample but forms patches on the same terrace. u-BL1 share similar properties with BL0, albeit withmore variability. These BLs have a strikingly larger overall intensity than BL with graphene on top. Thesignal high frequency side onset upshifts upon graphene coverage, unexplainable by a simple straineffect. Two fine peaks (1235, 1360 cm1), present for epitaxial monolayer and absent for BL and transferred graphene. These findings point to a coupling between graphene and BL.