Polyorganosiloxane

The siloxane Si—O link has a number of interesting properties which are relevant to the properties of the polyorganosiloxanes. TTiese will be dealt with later. 

The polyorganosiloxanes are generally prepared by reacting chlorosilanes with water to give hydroxyl compounds which then condense to give the polymer structure, e.g. 

The pioneering work on polyorganosiloxanes dates back to 1863-1871, to the studies of Friedel, Crafts8 "10) and Ladenburg 11 However, it was F. S. Kipping and his coworkers who were first to demonstrate the polymeric siloxane structures in the early 1900 s12). Unfortunately, since their interest was mainly in small molecules, they did not recognize the importance of the polymers and polymerization in this field 13). 

The repeating unit of a polyorganosiloxane consists of alternating silicon-oxygen atoms, in which two monovalent organic radicals are attached to each of the silicon atoms as shown below ... 

Table 8. Possible variations in the backbone composition of polyorganosiloxanes ...

McGrath, /. E, Dunson, A L., Hedrick,l L.i Synthesis and Characterization of Segmented Poly-imide-Polyorganosiloxane Copolymers. Vol. 140, pp. 61-106. 

Andrianov and Zhdanov have developed a method for the synthesis of polymers containing heterochain and carbon-chain units by free-radical copolymerization of metal-containing polyorganosiloxanes bearing a pendant vinyl group with vinyl monomers. The copolymers thus obtained display increased thermal stability and can be used for the production of laminated plastics, adhesives and other valuable materials 53),... 

An elastomer of the silicone family (see Silicones). It is a polyorganosiloxane, the backbone structure consisting of alternating silicone and oxygen atoms with organic groups, usually methyl, vinyl or phenyl radicals, attached to the silicon member. 

This is where all polyorganosiloxanes (silicones) start. The methods of the preparation of silicone monomers and their precursors have not changed significantly since the beginning of silicone technology. Functional silanes are synthesized by one of the following methods 3... 

A unique set of physical properties of polyorganosiloxanes, and the versatility of chemistries available in the preparation of macromolecules and their assemblies with growing complexity, result in a huge range of novel applications. However, this does not mean that the more traditional silicone materials have become less common.5... 

Parsonage, J. R. Kendrick, D. A. Silicate Sources of Polyorganosiloxane Materials A Brief Review. In Silicon-Containing Polymers-, Jones, R. G., Ed. Special Publication 166 - Royal Society of Chemistry Cambridge, 1995 pp 98-106. 

Godovsky, Y. K. Makarova, N. N. Matukhina, E. V. Mesophase Behavior and Structure of Mesophases in Cyclolinear Polyorganosiloxanes. In Silicones and Silicone-Modified Materials, Clarson, S. J., Fitzgerald, J. J., Owen, M. J., Smith, S. D., Eds. ACS Symposium Series 729 American Chemical Society Washington, DC, 2000 pp 98-114. 

Schmidt, R. G. Badour, L. R. Gordon, G. V. Modulus Reduction Mechanism of Trimethylsiloxy Silicates in a Polyorganosiloxane. In... 

Plasma surface cleaning (Ar-02) of the metal substrate is critical for good interfacial bonding with the subsequent coating. XPS and IR analyses show that the plasma-deposited silane polymers are essentially polyorganosiloxane in nature. 

Because of their chemical inertness, low surface tension and antisurfactant activity polyorganosiloxane (silicone) oils have found varied applications in medicine. These have included use as an artificial lubricant for arthritic joints191, as a means of soft tissue augmentation, and as an additive in creams and oils for burn treatment. Di-methylpolysiloxane fluids have been injected as replacement for aqueous and vitreous humour in eyes. Reactive organosilicon compounds comprise a new class of potential prophylactic and therapeutic agents192. Protection against atherosclerosis... 

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