Tetrabutylammonium bromide assisted preparation of monodispersed submicrometer silica particles

In this work, we demonstrate a new, facile approach for preparation of monodispersed, submicrometer silica particles via a tetrabutylammonium bromide (TBABr) assisted Stöber method. Sizes of the resulting silica particles increased from 0.39 to 1.08 μm with polydispersity lower than 5 % while the concentration of TBABr in the reaction media was elevated from 0 to 20.0 mM. The presence of TBABr molecules was able to effectively suppress the condensation rate of silanol monomers during the Stöber reaction, which, in turn, slowed the formation of silica seeds and thus accounted for growth of large silica particles. The use of tetraethylammonium bromide (TOABr), a quaternary ammonium agent with longer alkyl chains, instead of TBABr, yielded monodisperse silica particles more hydrophobic in character, making it feasible to tailor the surface properties of the as-prepared silica particles.