For most of the materials developed at AIME, and generally in ICGM, tailored or designed surfaces and interfaces are important, both as model systems for detailed study of processes that occur on complex materials and to design materials with new properties for use, such as clean processes for the environment or energy conversion and storage. The complexity of multi-component streams and effluents in which the action of materials is investigated, is a common characteristic of these applications.
Research on interfacial activity and properties of colloidal systems, natural or synthetic materials (porous, powdered, lamellar, and hybrid), on the one hand, and systematic investigation of the interfacial mechanisms involved, on the other hand, are pursued through experimental and modelling studies following the original research strategy and methodology developed at AIME. Our main priority is to collect information about the co-operative or competitive interactions involved, the chemical structure and orientation of molecular species (electrically neutral or charged) at interfaces, as well as the structural and textural evolution of interfaces in use.
Besides more classical methods applied to study the equilibrium, kinetic, and energetic aspects of the interfacial phenomena, modern interfacial calorimetry provides complementary information at the macroscopic level. The Nuclear Magnetic Resonance (NMR) spectroscopy (1H and 129Xe NMR) is used to probe for interactions and orientations of some molecular species at the solid-liquid or solid-gas boundary. Furthermore, a new in-situ technique based on the principle of non-linear optics (Second Harmonic Generation, SHG) is actually tested in order to validate the use of our integrated approach for the study of solid-liquid interfaces at the microscopic level. Finally, advanced phenomenological modelling assisted by computer-aided conventional or DFT simulation methods is applied to interpret data obtained from various experiments (e.g., X-ray diffraction, neutron imaging, IR spectroscopy, measurement of adsorption isotherms, calorimetry). Here, the objective is to describe the structure and surface properties of specific porous materials with a view of elucidating the mechanisms of adsorption and diffusion of molecules and ions at various interfaces.
The approach that combines experimental and theoretical aspects of materials and related interfacial phenomena also provides important indications for further rationalisation of the materials design and elaboration. Various components of surface energy (e.g., surface acidity/basicity, surface hydrophobic/hydrophilic character, or surface charge density) and surface curvature effects due to nanometric dimensions of pores or particles are described by following the specific interactions of selected molecular probes (electrically neutral or charged), with porous solids or nanoparticles.
Competitive adsorption of ionized molecular species (e.g., heavy metals, radionuclides, natural organic matter, dyestuffs, and drugs) at electrified interfaces (e.g., zeolites, ion exchange resins, ionosilicas, MOFs, clays, layered double hydroxides) is the main interfacial phenomenon underlying environmental remediation and clean energy applications. The results and conclusions inferred from fundamental research are utilized for optimization of these processes under real industrial conditions and also for conception of new materials dedicated to such applications, in collaboration with various university and industrial partners (ANR DECLIQ, SLIMCAT, CAMOMILS; CNRS NEEDS; GDR PROMETHEE; Maturation Initiale SATT AxLR).
List of former PhD and post-doctoral :
The following specific instruments are used to date: Zeta-Sizer and HPPS, potentiometric titration and conductometry systems, surface tension measurement techniques, total and organic carbon analyser, HPLC, Voltammetry Computrance system, UV-Vis spectrometer with an integrating sphere. They are supplemented by a non-linear optical device and the instruments available at the PAC Balard (Nacelles n°3 and n° 8).