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