The impact of reaction time on the hierarchical structure of mesoporous silica synthesized via modified stöber method

An investigation was conducted to observe the transformation of mesoporous silica nanoparticles (MSN) prepared using the modified Stober method with a cetyltrimethylammonium bromide (CTAB) template and varying aging periods. The hierarchical structure of the mesoporous silica nanostructure was analyzed using electron microscopy (FE-SEM and TEM) measurements, N2 adsorption, and small-angle X-rays scattering (SAXS). A comprehensive study using these instruments revealed that aging time significantly affected the morphology, pore structures, surface area, and pore size of the particles. It was observed that mesoporous silica grown in diverse morphologies from spherical nanoparticles, irregular particles, and nano-rods with an increase in aging time for 12 h, 18 and 24 h respectively. The SAXS and N2 adsorption measurements unveiled an intriguing relationship where the pore radius and surface area of MSN decreased with longer maturation times, reducing from 4.77 nm to 2.65 nm and from 849.43 m²/g to 572.85 m²/g, respectively. The results of the SAXS analysis also indicated a change in the pore structure due to prolonged reaction time, transitioning from a hexagonal structure to a loss of its orderedness. These findings play a crucial role in enhancing our understanding of how aging time influences the formation mechanism of MSNs for their diverse applications.