Investigating the Effect of Ultrasonification Time on Transition from Monolithic Porous Network to Size-Tunable Monodispersed Silica Nanosphere in Stöber Method

Uniform colloidal monodispersion of silica nanospheres were synthesized via Stöber method using ammonia as a basic catalyst. The effect of TEOS, EtOH, and H2O concentrations on the particle size and morphology were investigated. On the results, increasing in ultrasonication time as a new parameter from 12 to 45 min led to transition from monolithic porous network to homogenous nanospheres due to possessing enough time for micelle growth. Decreasing in TEOS concentration from 0.067 to 0.012 mol L1 and increasing in H2O concentration from 3 to 14 mol L^-1 at NH4OH concentration of 14 mol L^-1 accelerated the rate of hydrolysis and condensation of [Si (OC2H5)4X(OH)X]. Also, EtOH solvent prevented micelle aggregation and formed the spheres with the smallest variance in the size distribution.