Toolbox for 3D imaging and modeling of porous media: Relationship with transport properties

Abstract

Porous media can be considered as interfacial systems where an internal surface partitions and fills the space in a complex way. Meaningful structural features appear on a length-scale where physical chemistry plays a central role either to impose a specific organisation on the material or to strongly modify the dynamics and the thermodynamics of the embedded fluids. A key issue is to understand how the geometrical and interfacial confinement affects numerous phenomena such as molecular diffusion, excitation relaxation, reaction kinetics, phase transitions, adsorption and capillary condensation. We will first review some experimental techniques able to image the 3D structure of disordered porous media. In the second part, we will analyse the geometrical and particularly some topological properties of a disordered porous material. We will discuss the interest and the limits of several strategies for obtaining 3D representations of various pore networks starting from an incomplete set of morphological characterisations. Finally, connection between geometry and diffusive transport will be presented, with emphasis on the application of pulsed gradient spin echo NMR technique as a tool for a multiscale analysis of transport in a confining geometry.