Strong Silica Monoliths with Large Mesopores Prepared Using Agarose Gel Templates

Mesoporous silica pellets with controllable shape and pore size were prepared using agarose gel templates. Robust (compressive strength of 3.3−25.1 MPa), crack-free silica monoliths have been produced with large mesopores (14−23 nm), high surface areas (410−540 m² g⁻¹), and large pore volumes (1.1−1.2 cm³ g⁻¹). The synthesis was achieved by infusing preformed agarose gels with tetraethyl orthosilicate and the nonpolar condensation catalyst tetrabutyl ammonium fluoride. The infiltrated gels were transferred to water to initiate hydrolysis and condensation of the silica precursor. Fluoride catalyzed the gelation of silica in a matter of minutes; hence, the oxide maintained the shape of the agarose pellet. The mesopore size could be modified by altering the weight percent of agarose gel used. The method employed here is simple and reproducible. As these materials have such large mesopore dimensions, they could be used as hard templates or could be specifically functionalized for use in environmental remediation, as environmentally responsive materials, biocatalysts, or catalysts.