Ambient-temperature porogen-free method for preparation of silica-based macroporous materials

This work was supported by a Czech Science Foundation (GACR) grant 16-22997S and a Specific University Research – grant No A1_FCHI_2021_005. This publication is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant agreement No. 847413. Scientific work published as part of an international co-financed project founded from the program of the Minister of Science and Higher Education entitled "PMW" in the years 2020 - 2024; agreement no. 5005/H2020-MSCA-COFUND/2019/2.

The presented work focuses on the synthesis of silica-based macroporous aggregates composed of silica nanoparticles using a template-free method. To improve the mechanical strength of the prepared fractal-like aggregates, the silica precursor tetraethyl orthosilicate (TEOS) is used during nanoparticle aggregation. The obtained results confirm the possibility to tailor the pore size distribution (PSD) simply by using primary particles of various sizes. The prepared porous materials have a porosity ranging from 60% to 74% with a specific surface area between 10 and 200 m2/g and an average pore diameter from 30 to 1300 nm. Functionalization of the aggregate surface was done by replacing part of TEOS with a silica precursor that contained desired functional groups. This was demonstrated by preparing macroporous aggregates with carboxyl, amine and epoxy functional groups. The application of prepared aggregates was demonstrated by immobilization of urease from Canavalia ensiformis resulting in high enzyme activity compare to free enzymes.