Mesoporen

Mesopores are pores with diameters between 2 and 50 nanometers. In German-language contexts, the term Mesoporen is used for these pores. The designation sits between micropores (<2 nm) and macropores (>50 nm). Materials with mesoporous networks offer high surface areas, accessible pore channels, and tunable pore sizes, which can enhance interactions with guest molecules in catalysis, adsorption, separation, and delivery applications.

The term is most often associated with mesoporous silica, but mesoporosity also occurs in carbons and some inorganic-organic frameworks. Well-known examples include MCM-41 and SBA-15, which feature highly ordered hexagonal pore arrays, as well as KIT-6, which forms a three-dimensional mesoporous network. Pore geometry and connectivity influence diffusion and reactivity.

Synthesis commonly relies on templating. Soft templating uses surfactants or block copolymers that assemble into micelles or liquid-crystal phases around silica or carbon precursors; after condensation and removal of the template, mesopores remain. Hard templating (nanocasting) uses pre-formed templates to create mesoporous replicas. Template removal is typically achieved by calcination or solvent extraction.

Characterization relies on gas sorption measurements to yield surface area, pore volume, and pore size distribution (often via BET and BJH analysis). Transmission electron microscopy and small-angle X-ray scattering reveal pore order and connectivity. Typical mesoporous silica show surface areas from several hundred to over a thousand square meters per gram and pore diameters from 2 to 50 nm.

Applications span catalysis, adsorption and separation, drug delivery, and energy storage. The main advantages are accessible interior surfaces and tunable pore structures; limitations include thermal stability, chemical stability under reaction conditions, diffusion of bulky molecules, and challenges in scalable synthesis with uniform porosity.