Growth of nanoporous silica spherical particles by the Stöber method combined with supramolecular templating approach

Nanoporous silica spherical particles with narrow particle size distributions (standard deviation: 0.03-0.22) were synthesized by the Stöber method combined with supramolecular templating approach using tetraethoxysilane and cetyltrimethylammonium chloride. The reaction was conducted at 276 K to observe particle growth. Particles formed after the reaction for ca. 0.5 h, as shown by the fact that the solution became turbid. After the reaction for 0.5 h, particles with an average particle size of 440 nm in diameter were collected by filtration. The particles grew until the silica source was completely consumed. This took 50 h under the present reaction condition. The average particle size reached to ca. 1.8 μm at this stage. The calcined particles were porous with the surface areas of 380-1060 m ²g^-1 and the pore diameter of 1.6-2.0 nm.