Title: Silicones
Literature References: Broad family of synthetic polymers containing a repeating silicon-oxygen backbone with organic side groups attached via carbon-silicon bonds. Classified into three major types: fluids, resins and elastomers. The name was coined by F. S. Kipping under the supposition that the compounds were analogous to ketones; now used to designate a variety of complex polymeric siloxanes which may be linear, branched or cross-linked. Structural unit is represented by the formula, [RnSiO(4-n/2)]m, where n = 1-3 and m > 1. R groups are usually methyl, longer alkyl, fluoroalkyl, phenyl, vinyl, alkoxy or alkylamino. Silicones are characterized by thermal and oxidative stability, chemical inertness, resistance to weathering, good dielectric strength and low surface tension. Prepd commercially by the direct reaction of silicon with an organic halide, hydrolysis of the resulting organohalosilanes and condensation of the unstable diols. Review of chemistry, properties and uses: B. Hardman, A. Torkelson in Encyclopedia of Polymer Science and Engineering vol. 15 (Wiley-Interscience, New York, 1989) pp 204-308. Review of silicone surfactants: B. Grüning, G. Koerner, Tenside Surfactants Deterg. 26, 312-317 (1989); and their uses in cosmetics and toiletries: C. Gould, Spec. Chem. 11, 354-359 (1991). Clinical use of silicone elastomers in reconstructive surgery: M. B. Habal in Advances in Biomedical Polymers, C. G. Gebelein, Ed. (Plenum Press, New York, 1987) pp 17-29. Review of properties and commercial uses of silicone fluids: D. H. Demby et al. in Synthetic Lubricants and High-Performance Functional Liquids, R. L. Shubkin, Ed. (Marcel Dekker, New York, 1993) pp 183-203.
Derivative Type: Polydimethylsiloxane see Dimethicone
Derivative Type: Polyether copolymers
Additional Names: Silicone polyethers; dimethicone copolyols; silicone glycol copolymers; silicone glycols
Literature References: Branched siloxanes modified at the chain ends with a polyether, e.g. polyoxyethylene and/or polyoxypropylene. Trade marks for such products include: Abil (Goldschmidt Chem.) , Stilwet L (Union Carbide) .
Use: As lubricants; wetting agents; defoamers; surfactants; hydraulic oils; dielectric oils; protective coatings; adhesives and caulking compounds; release agents; in paints, enamels, and varnishes; water repellents for textiles, paper, masonry, and concrete; damping fluids; electrical insulation; dental molds; medical implants; contact lenses; and in cosmetic and pharmaceutical formulations. A specialty product known as "bouncing putty" or "silly putty" has unusual rheological properties which allow it to be stretched, shattered, molded, or to rebound like rubber when dropped on hard surface. |