Study on the three-stage growth of silica nanoparticles prepared by the drop-by-drop precipitation method

The growth of silica nanoparticles prepared by adding sulfuric acid dropwise into waterglass is followed using SAXS. Changes in the particle size and relative particle numbers during the 60-min precipitation are calculated. The data reveal three-stage growth of silica nanoparticles, which are the monomer accumulation stage, the growth stage and the pore formation stage. The hydrolysis and condensation of silicic acid are analyzed by monitoring conductivity to explain the growth mode. These results show that insufficient H+ makes hydrolysis the main reaction in the monomer accumulation stage, while condensation is dominant in the growth stage. The Liftshitz-Slyozov-Wagner (LSW) model is applied to fit the particle size changes occurring in the growth stage, which suggests a surface reaction-controlled mechanism. The condensation reaction is studied with Gaussian calculations. The change in particle morphology during the third stage is also investigated using TEM and nitrogen isothermal adsorption to analyze the formation of pore structures. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The growth process of silica nanoparticles prepared by adding sulfuric acid dropwise into waterglass was investigated. Three stages of growth were observed, and the hydrolysis and condensation reactions were analyzed. The particle size changes in the growth stage were fitted using the LSW model, and the formation of pore structures was studied.