Silsesquioxanes: POSS^® Nanohybrids

Hybrid inorganic–organic composites are an emerging class of new materials that hold significant promise.¹ Materials are being designed with the good physical properties of ceramics and the excellent choice of functional group chemical reactivity associated with organic chemistry. New silicon-containing organic polymers, in general, and polysilsesquioxanes, in particular, have generated a great deal of interest because of their potential replacement for, and compatibility with silicon-based inorganics in the electronics, photonics, and other materials technologies.^2-4

Hydrolytic condensation of trifunctional silanes yields network polymers or polyhedral clusters having the generic formula (RSiO_1.5)n.^5,6 Hence, they are known by the "not quite on the tip of the tongue" name silsesquioxanes. Each silicon atom is bound to an average of one and a half (sesqui) oxygen atoms and to one hydrocarbon group (ane). Typical functional groups that may be hydrolyzed/condensed include alkoxy- or chlorosilanes, silanols, and silanolates.⁷

Silsesquioxanes Technical Resource

References
(1) Hybrid Organic/Inorganic Materials, Proceedings of the Materials Research Society Spring 2000 Meeting; Laine, R. M., Sanchez, C., Giannelis, E., Brinker, C. J., Eds.; Vol. 628.
(2) Hybrid Inorganic-Organic Polymers. In Polymer Preprints; Stoney, R. F., Ed.; American Chemical Society: Washington D.C., 2000; Vol. 41, pp 502–625.
(3) Symposium on "3-D Silicon-Oxygen Cages: Materials for the 21st Century", American Chemical Society, 222nd National Meeting, Aug. 26-30, 2001; Primary sponsor: Materials Chemistry Secretariat.
(4) Provatas, A. et al. J. Organomet. Chem. 1998, 565, 159.
(5) Baney, R. H. et al. Chem. Rev. 1995, 95, 1409.
(6) Lichtenhan, J. D. Silsesquioxane-Based Polymers, The Polymeric Materials Encyclopedia: Synthesis, Properties and Applications; Salamone, J. C., Ed.; CRC Press: Boca Raton, Florida, 1996; p 7768.
(7) Brook, M.A .; Silicon in Organic, Organometallic, and Polymer Chemistry; Wiley: New York, 2000.