Formation of reactive aerogels and their reactivity in aqueous media. Wettability induces hydrophobic vs. hydrophilic selectivity

Aerogels were formed from organogels of diamides by a supercritical drying process. The used organogels are composed of self-assembled nanotubes of 29 nm in diameter. SEM studies reveal that the resulting aerogels are made of fibers with diameters comprised between 40 and 200 nm, corresponding to bundles of the starting nanotubes, while WAXS indicated that most of the crystalline structure detected in the self-assemblies of the starting gel is preserved in aerogels. Two different reactive diamides bearing respectively an alkynyl and an azido function were investigated. We have tested the reactivity of the resulting aerogels under copper-catalyzed azide-alkyne cycloaddition in aqueous solution. These aerogels react easily with hydrophobic compounds although reactants are in separate phases. In contrast, they do not react with hydrosoluble compounds, because of their superhydrophobicity.