Synthesis and characterization of hierarchical porous materials incorporating a cubic mesoporous phase

Abstract

Hierarchical silica porous materials have been successfully synthesized using polystyrene nanospheres as macropore template, triblock copolymer Pluronic F127 as mesopore template, tetramethyl orthosilicate as silica source and ethanol as cosurfactant. The obtained materials were characterized by XRD, TG-DTA, N₂ adsorption, SEM, TEM and AFM. These materials consist of a system of macropores with diameters of ca. 300 nm whose walls are filled with mesoporous material with average pore diameter 10 nm. The materials are also integrated with non-crystalline micropores. The XRD pattern indicates one sample with structure Fmm, which consists of the mesopores organized in a face-centred cubic arrangement. The hierarchical porous material created after template extraction by solvent washing exhibited a BET surface area of 277 m² g⁻¹. Following calcination the material has a BET surface area of 469 m² g⁻¹. Such properties give these materials potential for a wide range of applications in which high surface area combined with a well-defined system of pores at different length scales are required, such as adsorption, catalysis and enzyme immobilization.