Chapter 8: Hyperpolarized ¹²⁹Xe NMR in Materials Sciences: Pore Structure, Interconnectivity and Functionality

Hyperpolarized ¹²⁹Xe NMR is widely used in material sciences for probing structures, interconnectivity and functionality of micro- and mesopores. The extent of interconnectivity between micro- or mesopore domains, the size and geometry of the pores and the functionality of the pore surfaces greatly affect materials properties such as accessibility, selectivity, ion transport and diffusion. The pore geometry in most porous materials, even in ordered mesoporous silica, is complex and characterized by interconnected cages, channels and micropores. As a result of these complex topographies, characterization of interconnectivity of the pores in micro or mesoporous materials is often challenging and mandates for several methods. The most common techniques such as small angle X-ray or neutron scattering and gas absorption, however, do not provide direct information on how channels and cages are connected. In this review chapter, we emphasize the application of hyperpolarized ¹²⁹Xe NMR in probing structures, interconnectivity and functionality for a variety of mesoporous materials including (a) functionalized ordered mesoporous materials; (b) polymer aerogels; (c) hierarchically ordered mesoporous materials; (d) infiltrated and doped mesoporous materials; and (e) porous electrode materials.