Stöber process

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The Stöber process is a physical chemistry process for the generation of monodisperse particles of silica. The process was discovered in 1968 by Werner Stöber et al.[1] building on earlier work by G. Kolbe in published in 1956.[2] The topic has since been widely researched. Tetraethyl orthosilicate is added to an excess of water containing a low molar-mass alcohol such as ethanol and containing ammonia. The resulting solution is then stirred. The resulting silica particles have diameters between 50 and 2000 nanometers depending on type of silicate ester used, type of alcohol used and volume ratios.[3] A particle size up to 1000 micrometres has been reported in a modified emulsion technique.[4] The reactions taking place are hydrolysis of the silyl ether to a silanol followed by condensation reactions. The particles have been analysed by light scattering.[5][6]

The process is believed to take place via a LaMer model (monomer addition) in which nucleation is a fast process, followed by a particle growth process without further nucleation.[7][8][9] In an alternative model called controlled aggregation, the particles grow by aggregation of smaller particles.[10][11][12][13][14] This model is supported by microgravity experiments [15] and by SAXS analysis.[16] Kinetics have been investigated with variation in pH.[17]

Reported morphological variations are a PEG graft [18] and core-shell morphologies based on cyclen,[19] polyamines [20] and polystyrene.[21]

Microporous silica particles can be obtained through organic templating followed by calcination. Reported organic additives for this process are cetyltrimethylammonium bromide [22][23][24] and glycerol [25]

Carbon spheres[edit]

The synthesis of carbon-based spheres has been reported in a similar process with resorcinol and formaldehyde. [26][27]


  1. ^ Controlled growth of monodisperse silica spheres in the micron size range Journal of Colloid and Interface Science, Volume 26, Issue 1, January 1968, Pages 62-69 Werner Stöber, Arthur Fink, Ernst Bohn doi:10.1016/0021-9797(68)90272-5
  2. ^ Kolbe, G., Ph.D. thesis, Jena, Germany, 1956.
  3. ^ G.H. Bogush, M.A. Tracy, C.F. Zukoski IV, Preparation of monodisperse silica particles: Control of size and mass fraction, Journal of Non-Crystalline Solids, Volume 104, Issue 1, August 1988, Pages 95-106, ISSN 0022-3093, doi:10.1016/0022-3093(88)90187-1.
  4. ^ J. Esquena, R. Pons, N. Azemar, J. Caelles, C. Solans, Preparation of monodisperse silica particles in emulsion media, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volumes 123-124, Frontiers in Colloid Chemistry an International Festschrift to Professor Stig E. Friberg, 15 May 1997, Pages 575-586, ISSN 0927-7757, doi:10.1016/S0927-7757(96)03830-7
  5. ^ A.K. Van Helden, J.W. Jansen, A. Vrij, Preparation and characterization of spherical monodisperse silica dispersions in nonaqueous solvents, Journal of Colloid and Interface Science, Volume 81, Issue 2, June 1981, Pages 354-368, ISSN 0021-9797, doi:10.1016/0021-9797(81)90417-3
  6. ^ A. Van Blaaderen, J. Van Geest, A. Vrij, Monodisperse colloidal silica spheres from tetraalkoxysilanes: Particle formation and growth mechanism, Journal of Colloid and Interface Science, Volume 154, Issue 2, December 1992, Pages 481-501, ISSN 0021-9797, doi:10.1016/0021-9797(92)90163-G
  7. ^ T. Matsoukas, Erdogan Gulari, Dynamics of growth of silica particles from ammonia-catalyzed hydrolysis of tetra-ethyl-orthosilicate, Journal of Colloid and Interface Science, Volume 124, Issue 1, July 1988, Pages 252-261, ISSN 0021-9797, doi:10.1016/0021-9797(88)90346-3
  8. ^ Themis Matsoukas, Erdogan Gulari, Monomer-addition growth with a slow initiation step: A growth model for silica particles from alkoxides, Journal of Colloid and Interface Science, Volume 132, Issue 1, 1 October 1989, Pages 13-21, ISSN 0021-9797, doi:10.1016/0021-9797(89)90210-5
  9. ^ Themis Matsoukas, Erdogan Gulari, Self-sharpening distributions revisited--polydispersity in growth by monomer addition, Journal of Colloid and Interface Science, Volume 145, Issue 2, September 1991, Pages 557-562, ISSN 0021-9797, doi:10.1016/0021-9797(91)90385-L
  10. ^ G.H Bogush, C.F Zukoski IV, Studies of the kinetics of the precipitation of uniform silica particles through the hydrolysis and condensation of silicon alkoxides, Journal of Colloid and Interface Science, Volume 142, Issue 1, 1 March 1991, Pages 1-18, ISSN 0021-9797, doi:10.1016/0021-9797(91)90029-8
  11. ^ G.H Bogush, C.F Zukoski IV, Uniform silica particle precipitation: An aggregative growth model, Journal of Colloid and Interface Science, Volume 142, Issue 1, 1 March 1991, Pages 19-34, ISSN 0021-9797, doi:10.1016/0021-9797(91)90030-C
  12. ^ Kangtaek Lee, Arun N. Sathyagal, Alon V. McCormick, A closer look at an aggregation model of the Stober process, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 144, Issues 1-3, 20 December 1998, Pages 115-125, ISSN 0927-7757, doi:10.1016/S0927-7757(98)00566-4
  13. ^ D. L. Green, J. S. Lin, Yui-Fai Lam, M. Z. -C. Hu, Dale W. Schaefer, M. T. Harris, Size, volume fraction, and nucleation of Stober silica nanoparticles, Journal of Colloid and Interface Science, Volume 266, Issue 2, 15 October 2003, Pages 346-358, ISSN 0021-9797, doi:10.1016/S0021-9797(03)00610-6
  14. ^ Hiroki Okudera, Atsushi Hozumi, The formation and growth mechanisms of silica thin film and spherical particles through the Stober process, Thin Solid Films, Volume 434, Issues 1-2, 23 June 2003, Pages 62-68, ISSN 0040-6090, doi:10.1016/S0040-6090(03)00535-2
  15. ^ Effect of Microgravity on the Growth of Silica Nanostructures David D. Smith, Laurent Sibille, Raymond J. Cronise, Arlon J. Hunt, Steven J. Oldenburg, Daniel Wolfe, and Naomi J. Halas Langmuir, 2000, 16 (26), pp 10055–10060 doi:10.1021/la000643s
  16. ^ Time-Resolved SAXS Study of Nucleation and Growth of Silica Colloids D. Pontoni,, T. Narayanan,, and, A. R. Rennie Langmuir 2002 18 (1), 56-59 doi:10.1021/la015503c
  17. ^ Kinetics of Sol Particle Formation as a Function of pH Studied by Viscosity Measurements in Silica Solutions Wolfram Vogelsberger,, Andreas Seidel, and, Tilo Breyer Langmuir 2002 18 (8), 3027-30334 doi:10.1021/la0114878
  18. ^ Macroporous silica using a "sticky" Stöber process Rebecca Cademartiri, Michael A. Brook, Robert Pelton and John D. Brennan J. Mater. Chem., 2009, 19, 1583-1592 doi:10.1039/B815447C
  19. ^ Modification of the Stöber Process by a Polyazamacrocycle Leading to Unusual Core−Shell Silica Nanoparticles Sylvie Masse, Guillaume Laurent, Françoise Chuburu, Cyril Cadiou, Isabelle Déchamps, and Thibaud Coradin Langmuir, 2008, 24 (8), pp 4026–4031 doi:10.1021/la703828v
  20. ^ Influence of cyclic polyamines on silica formation during the Stöber processSylvie Masse, Guillaume Laurent and Thibaud Coradin Phys. Chem. Chem. Phys., 2009, 11, 10204-10210 doi:10.1039/B915428K
  21. ^ Xuefeng Ding, Jingzhe Zhao, Yanhua Liu, Hengbin Zhang, Zichen Wang, Silica nanoparticles encapsulated by polystyrene via surface grafting and in situ emulsion polymerization, Materials Letters, Volume 58, Issue 25, October 2004, Pages 3126-3130, ISSN 0167-577X, doi:10.1016/j.matlet.2004.06.003
  22. ^ Grün, M., Lauer, I. and Unger, K. K. (1997), The synthesis of micrometer- and submicrometer-size spheres of ordered mesoporous oxide MCM-41. Advanced Materials, 9: 254–257. doi:10.1002/adma.19970090317
  23. ^ Shiquan Liu, Lingchao Lu, Zhongxi Yang, Pegie Cool, Etienne F. Vansant, Further investigations on the modified Stober method for spherical MCM-41, Materials Chemistry and Physics, Volume 97, Issues 2-3, 10 June 2006, Pages 203-206, ISSN 0254-0584, doi:10.1016/j.matchemphys.2005.09.003
  24. ^ Larger Scale Syntheses of Surfactant-Templated Nanoporous Silica Spherical Particles by the Stöber Method Kumiko KAMBARA, Naoki SHIMURA and Makoto OGAWA Journal of the Ceramic Society of Japan Vol. 115 (2007) , No. 1341 (May) pp.315-318 doi:10.2109/jcersj.115.315
  25. ^ R. Vacassy, R. J. Flatt, H. Hofmann, K. S. Choi, R. K. Singh, Synthesis of Microporous Silica Spheres, Journal of Colloid and Interface Science, Volume 227, Issue 2, 15 July 2000, Pages 302-315, ISSN 0021-9797 doi:10.1006/jcis.2000.6860
  26. ^ Liu, J., Qiao, S. Z., Liu, H., Chen, J., Orpe, A., Zhao, D. and Lu, G. Q. (2011), Extension of The Stöber Method to the Preparation of Monodisperse Resorcinol–Formaldehyde Resin Polymer and Carbon Spheres. Angewandte Chemie International Edition, 50: 5947–5951. doi:10.1002/anie.201102011
  27. ^ Lu, A.-H., Hao, G.-P. and Sun, Q. (2011), Can Carbon Spheres Be Created through the Stöber Method?. Angewandte Chemie International Edition, 50: 9023–9025. doi:10.1002/anie.201103514