Hierarchically Porous Silica with Ordered Mesostructure from Confinement Self-Assembly in Skeleton Scaffolds

Hierarchically porous silica materials have been synthesized through a confinement self-assembly approach in the skeletal scaffolds of commercial polyurethane (PU) foams. Macroporous/mesoporous silica materials with a well-ordered two-dimensional (2-D) hexagonal ( p 6 mm ) mesostructure have been synthesized in an acidic solution using tetraethoxysilane as a precursor, triblock copolymer Pluronic P123 as a mesostructural template, and PU foams with three-dimensional (3-D) interconnecting strut networks as a macrostructure scaffold. By controlling the volume ratio of the cast silica sol to the PU foam scaffolds, hierarchically porous silica monoliths with various macropore structures can be obtained. The porous silica monoliths can be disassembled into uniform polyhedron-like particles. The porous silica polyhedrons exhibit macropores 100−500 μm in diameter, adjustable uniform mesopores (6.5−9.3 nm in diameter), high surface areas (340−780 m 2 /g), and large pore volumes (0.48−1.16 cm 3 /g). The resulting macroporous/mesoporous silica polyhedrons show an excellent adsorption and remove capability of Microcystin-LR in wastewater.