Gelled Electrolyte Containing Phosphonium Ionic Liquids for Lithium-Ion Batteries.

In this work, new gelled electrolytes were prepared based on a mixture containing phosphonium ionic liquid (IL) composed of trihexyl(tetradecyl)phosphonium cation combined with bis(trifluoromethane)sulfonimide [TFSI] counter anions and lithium salt, confined in a host network made from an epoxy prepolymer and amine hardener. We have demonstrated that the addition of electrolyte plays a key role on the kinetics of polymerization but also on the final properties of epoxy networks, especially thermal, thermo-mechanical, transport, and electrochemical properties. Thus, polymer electrolytes with excellent thermal stability (>300 °C) combined with good thermo-mechanical properties have been prepared.

Water sub-diffusion in membranes for fuel cells.

We investigate the dynamics of water confined in soft ionic nano-assemblies, an issue critical for a general understanding of the multi-scale structure-function interplay in advanced materials. We focus in particular on hydrated perfluoro-sulfonic acid compounds employed as electrolytes in fuel cells. These materials form phase-separated morphologies that show outstanding proton-conducting properties, directly related to the state and dynamics of the absorbed water.

The structural organization of seed oil bodies could explain the contrasted oil extractability observed in two rapeseed genotypes.

The protein, phospholipid and sterol composition of the oil body surface from the seeds of two rapeseed genotypes was compared in order to explain their contrasted oil extractability. In the mature seeds of oleaginous plants, storage lipids accumulate in specialized structures called oil bodies (OBs). These organelles consist of a core of neutral lipids surrounded by a phospholipid monolayer in which structural proteins are embedded.

In vivo measurement of the size of oil bodies in plant seeds using a simple and robust pulsed field gradient NMR method.

An easy to implement and convenient method to measure the mean size of oil bodies (OBs) in plant seeds is proposed using a pulsed field gradient nuclear magnetic resonance (PFGNMR) approach. PFGNMR is a well-known technique used to study either free or restricted diffusion of molecules. As triacylglycerols (TAG) are confined in OBs, analysis of their diffusion properties is a well-suited experimental approach to determine OB sizes.

NMR 1D-imaging of water infiltration into mesoporous matrices.

It is shown that coupling nuclear magnetic resonance (NMR) 1D-imaging with the measure of NMR relaxation times and self-diffusion coefficients can be a very powerful approach to investigate fluid infiltration into porous media. Such an experimental design was used to study the very slow seeping of pure water into hydrophobic materials. We consider here three model samples of nuclear waste conditioning matrices which consist in a dispersion of NaNO(3) (highly soluble) and/or BaSO(4) (poorly soluble) salt grains embedded in a bitumen matrix.

Almost ideal 1D water diffusion in imogolite nanotubes evidenced by NMR relaxometry.

The longitudinal proton relaxation rates R(1) of water diffusing inside synthetic aluminium silicate imogolite nanotubes are measured by fast field-cycling NMR for frequencies between 0.02 and 35 MHz at 25, 37 and 50 degrees C. We give analytical expressions of the dominant intermolecular dipolar spin-spin contribution to R(1) and to the transverse relaxation rate R(2).

Microscopic structure of heterogeneous lipid-based formulations revealed by 13C high-resolution solid-state and 1H PFG NMR methods.

Lipid-based formulations such as lip glosses that are very alike on the base of their components may have significant differences in their expected macroscopic properties as cosmetics. To differentiate such formulations, high-resolution (13)C NMR was performed under magic angle spinning to investigate the properties at both molecular and microscopic levels. Temperature studies were carried out and no polymorphism in the solid domains could be evidenced after the thermal treatment performed for obtaining the commercial lip glosses.

Microphase structure of poly(N-isopropylacrylamide) hydrogels as seen by small- and wide-angle X-ray scattering and pulsed field gradient NMR.

Above the lower critical solution temperature T(c) (ca. 34 degrees C), poly(N-isopropylacrylamide) hydrogels become weakly hydrophobic and undergo microphase separation. Macroscopic deswelling, however, is extraordinarily slow, the out-of equilibrium state of the gel being conserved for many days.

NMR and pulsed field gradient NMR approach of water sorption properties in Nafion at low temperature.

The water uptake and the water self-diffusion coefficient were measured in Nafion membranes at subzero temperatures. NMR spectroscopy was used to precisely quantify the actual concentration of water in membranes as a function of the temperature and their hydration rates at room temperature. We find that below 273 K the water concentration decreases with temperature to reach, at around 220 K, a limit value independent of the initial concentration.

In situ pulsed-field gradient NMR determination of the size of oil bodies in vegetable seeds. Analysis of the effect of the gradient pulse length.

We report a pulsed-field gradient NMR study of the size of the oil bodies in lettuce seeds. The pulsed-field gradient spin-echo method (PFGSE) was applied to measure the self-diffusion coefficient of triacylglycerol molecules (TAG) inside the oil bodies. The confined nature of TAG diffusion is used to determine the size dispersion of the oil bodies.

Water dynamics in ionomer membranes by field-cycling NMR relaxometry.

The dynamic behavior of water within two types of ionomer membranes, Nafion and sulfonated polyimides, has been investigated by field-cycling nuclear magnetic relaxation. This technique, applied to materials prepared at different hydration levels, allows to probe the proton motion on a time scale of the microsecond. The NMR longitudinal relaxation rate R(1) measured over three decades of Larmor angular frequencies omega is particularly sensitive to the host-water interactions and thus well suited to study fluid dynamics in restricted geometries.

Water dynamics in ionomer membranes by field-cycling NMR relaxometry.

The dynamic behavior of water within two types of ionomer membranes, Nafion and sulfonated polyimide, has been investigated by field-cycling nuclear magnetic relaxation. This technique, applied to materials prepared at different hydration levels, allows the proton motion on a time scale of microseconds to be probed. The NMR longitudinal relaxation rate R(1) measured over three decades of Larmor angular frequencies omega is particularly sensitive to the host-water interactions and thus well-suited to study fluid dynamics in restricted geometries.

Investigation of gamma-irradiated vegetable seeds with high-resolution solid-state 13C NMR.

13C solid-state NMR was used to investigate the effects of gamma radiation on vegetable seeds, Pisum sativum and Latuca sativa, at absorbed doses that inhibit their germination. By combining single-pulse excitation and cross-polarization experiments under magic angle spinning, both liquid and solid domains of seeds can be characterized. We showed that the liquid domains, mostly made of triacylglycerols (TAG), of vegetable seeds are not sensitive to radiation.