Hierarchical porous materials: Internal structure revealed by argon ion-beam cross-section polishing, HRSEM and AFM

High-resolution scanning electron microscopy coupled with argon ion-beam cross-section polishing and atomic force microscopy were used to reveal details about the interconnectivity of meso- and macroporous networks in silica hierarchical porous material. The material studied has ordered macro- and mesoporosity as well as a disordered microporosity that are created using organic templating agents. Latex spheres template the macro- porosity, mesophase self-assembly of block co-polymers template the mesoporosity and individual polymer chains template the microporosity. By polishing this composite material with an argon ion beam it is possible to reveal the internal structure with minimal structural damage. Direct imaging of the mesoporous network within such cross sections is possible using high-resolution scanning electron microscopy. These observations demonstrate a lack of interconnectivity between the mesoporous and macroporous networks.