Features of supercritical CO2 in the delicate world of the nanopores

This contribution highlights the main characteristic that makes supercritical CO2 (scCO(2)) a highly interesting solvent to perform both physical processing and chemical reactions to build or modify delicate porous nanostructures. Historically, the most promising developments of the supercritical fluid technology in the field of porous materials have been foaming of polymers, processing and/or impregnation of aerogels, and surface modification of micro and mesoporous solids. More recently, the technology has evolved to the synthesis of porous materials by developing reactive processes in scCO(2). One example is the synthesis of empty-pore threedimensional metal-organic frameworks (MOFs). This paper reviews process concepts of supercritical fluid methods applied to porous compounds, giving examples of materials produced in our own laboratory. The processing of disordered (polymers, aerogels, concrete) and ordered (zeolites, mesoporous silicas, MOFs) porous materials is addressed. Perspectives of future development of the technology in pharmaceutical formulations and CO2 capture applications are given.