A combined SAXS-shear analysis of polymer nanocomposites for the first time between parallel plates is presented. This set-up allows investigating microstructural changes accompanying macroscopic rheological phenomena, such as the Payne effect. The latter is known to induce filler network destruction and subsequent flocculation when the shear strain amplitude is increased or decreased, respectively. First, a detailed SAXS analysis of the microstructure of carbon black in styrene-butadiene nanocomposites is applied to a series of increasing filler loading. The average size and mass of primary particles and small aggregates are estimated using a model of inter-aggregate polydisperse hardsphere interactions. In a second time, the impact of a new geometry of the shear experiments with a horizontal X-ray beam passing through a disc-shaped nanocomposite on the SAXS pattern is analyzed in terms of sample heterogeneity (different positions), anisotropy (orientations), and sample thickness (transmission and heterogeneity). Application of our quantitative analysis shows that hot molding induces a slight anisotropy of the aggregate shapes into prolate ellipsoids oriented parallel to the rubber sheet. The Payne effect is then followed by scattering, surprisingly showing no modification of the intensity under oscillatory shear. Thus, the aggregate structure observed on the scale of standard SAXS is not broken up during Payne experiments, hinting at either an averaging effect over oscillation periods, or to the reorganization of large-scale agglomerate or network structures.

Mesoporous systems are ubiquitous in membrane science and applications due to their high internal surface area and tunable pore size. A new synthesis pathway of hydrolytic ionosilica films with mesopores formed by ionic liquid (IL) templating is proposed and compared to the traditional nonhydrolytic strategy. For both pathways, the multi-scale formation of pores has been studied as a function of IL content, combining results of thermogravimetric analysis (TGA), nitrogen sorption, and small-angle X-ray scattering (SAXS). The combination of TGA and nitrogen sorption provides access to ionosilica and pore volume fractions, with contributions of meso-and macropores. We then elaborate an original and quantitative geometrical model to analyze the SAXS data based on small spheres (Rs = 1 -2 nm) and cylinders (Lcyl = 10 -20 nm) with radial polydispersity provided by the nitrogen sorption isotherms. As a main result, we found that for a given incorporation of templating IL, both synthesis pathways produce very similar pore geometries, but the better incorporation efficacy of the new hydrolytic films provides a higher mesoporosity. Our combined study provides a coherent view of mesopore geometry, and thereby an optimization pathway of porous ionic membranes in terms of accessible mesoporosity contributing to the specific surface. Possible applications include electrolyte membranes of improved ionic properties, e.g., in fuel cells and batteries, as well as molecular storage.

Brillouin spectroscopy is a non-invasive method technique for visualizing the mechanical properties of biological samples with sub-micrometer resolution. However, to obtain 2D or even 3D maps, a high-contrast spectrometer is required to effectively reject spurious signals and isolate the signal of interest. In this work, we present an optimized two-stage virtually imaged phased array-based Brillouin spectrometer capable of achieving a contrast of at least 80 dB thanks to a new single diffraction mask, and thus with an unprecedentedly high overall transmission. Numerical simulations of the electric field propagation through the spectrometer and dedicated experiments validate the increase in contrast. We have used the newly developed Brillouin spectrometer coupled to a confocal microscope to obtain 1 h high-resolution 2D images of about 104 spectra of transparent dental pulp stem cells near a MgF2 interface as well as of the much less transparent porcine dentin material, demonstrating its overall stability and reliability.