Cyclodextrin-Based Pseudopolyrotaxanes as Templates for the Generation of Porous Silica Materials

The in situ formed supramolecular assemblies of cyclodextrins with nonionic surfactants, poly(ethylene glycol), poly(propylene glycol), and block copolymer, so-called pseudopolyrotaxanes, were used as porogens for the generation of porous silica materials. The resulting structures are characterized with nitrogen sorption experiments, transmission electron microscopy, and small-angle X-ray scattering. It was shown that the pore structure replicates the structure of the original supramolecular template, i.e., at pH 2.0, the cyclodextrins are threaded by the polymer, and a short tubelike morphology of the pores is found. At higher pH values, the aggregation of the pseudopolyrotaxanes toward bundle domains leads to larger pores.