Non-hydrolytic formation of silica and polysilsesquioxane particles from alkoxysilane monomers with formic acid in toluene/tetrahydrofuran solutions

Dylan J. Boday, Stephanie Tolbert, Michael W. Keller, Zhe Li, Jason T. Wertz, Beatrice Muriithi, Douglas A. Loy

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Silica and polysilsesquioxane particles are used as fillers in composites, catalyst supports, chromatographic separations media, and even as additives to cosmetics. The particles are generally prepared by hydrolysis and condensation of tetraalkoxysilanes and/or organotrialkoxysilanes, respectively, in aqueous alcohol solutions. In this study, we have discovered a new, non-aqueous approach to prepare silica and polysilsesquioxane particles. Spherical, nearly monodisperse, silica particles (600-6,000 nm) were prepared from the reaction of tetramethoxysilane with formic acid (4-8 equivalents) in toluene or toluene/tetrahydrofuran solutions. Polymerization of organotrialkoxysilanes with formic acid failed to afford particles, but bridged polysilsesquioxane particles were obtained from monomers with two trialkoxysilyl group attached to an organic-bridging group. The mild acidic conditions allowed particles to be prepared from monomers, such as bis(3-triethoxysilylpropyl)tetrasulfide, which are unstable to Stöber or base-catalyzed emulsion polymerization conditions. The bridged polysilsesquioxane particles were generally less spherical and more polydisperse than silica particles. Both silica and bridged polysilsesquioxane nanoparticles could be prepared in good yields at monomer concentrations considerably higher than used in Stöber or emulsion approaches.

Original languageEnglish (US)
Article number2313
JournalJournal of Nanoparticle Research
Volume16
Issue number3
DOIs
StatePublished - Mar 2014

Keywords

  • Bridged silsesquioxane particles
  • Emulsion
  • Formic acid
  • Non-hydrolytic
  • Non-polar solvents
  • Silica particles
  • Sol-gel
  • Stöber particles

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Atomic and Molecular Physics, and Optics
  • Modeling and Simulation
  • Materials Science(all)
  • Condensed Matter Physics

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