Assembly of SBA-15 into hierarchical porous monoliths replicating polymeric scaffolds

Abstract : This study reports the preparation of highly porous, SBA-15-based monolithic materials with pore sizes spanning over four scales (micro-/meso-/small macro-/large macro-pores). Two approaches were explored. The first one involves the preparation of PMMA scaffolds obtained from chemically-bonded beads and their further infiltration using SBA-15 slurries with suitable viscosity; while the second one directly uses the same amount of PMMA beads dispersed within the slurries. Emphasis was given to the comparison of the textural, structural, and mechanical properties obtained following each approach. Then, application of a thermal consolidation step and its influence over the monoliths properties was investigated, with an optimum observed at 950 °C. The second method systematically allowed reaching higher mechanical resistances (86 vs 32 kPa at 950 °C) for comparable specific surface areas (274 vs 290 m²/g at 950 °C), however at the expense of smaller macropores and lower ordering in the monoliths.