Tunable hierarchical porous silica materials using hydrothermal sedimentation-aggregation technique

• Hierarchical porous silicas with sub-100 nm macropores.
• Long range macrostructural ordering of siliceous materials.
• Formation of large mesoporous windows with size distribution depending on the duration of the hydrothermal treatment.
• Higher pore volume, surface area and thicker pore walls by simply expanding the hydrothermal aging time.

Herein, a simple and efficient synthesis based on a dual templating approach allow the preparation of tunable macroporous mesoporous silica materials. Macropores incorporation has been obtained using polymer spheres of well-defined size and their subsequent removal by thermal treatment allowed the independent control of the macropore size entrance between 200 nm and 50 nm. The addition of the block copolymer drives the formation of a second mesostructured skeleton, with a pore size centered around 4 nm, throughout the material framework. By a fine tuning of the sol–gel synthesis parameters (Polymer:TEOS ratio, aging conditions), we succeeded in guiding the SBA-15 rod-like morphology having randomly packed macropores to a derived SBA-15 with a homogeneous honeycomb macrostructure. Moreover, large mesoporous windows are generated between adjacent macropores. Hence, this simple one-pot synthesis approach, allowing scaling-up, offers fine tuning porosity at the macropore scale.

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