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Polysiloxanes & Polysilanes

  1. Amitabha Mitra,
  2. David A. Atwood

Published Online: 15 DEC 2011

DOI: 10.1002/9781119951438.eibc0187

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Mitra, A. and Atwood, D. A. 2011. Polysiloxanes & Polysilanes . Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. University of Kentucky, Lexington, KY, USA

Publication History

  1. Published Online: 15 DEC 2011

Abstract

Silicon-containing polymers, of which polysiloxanes and polysilanes are the most important ones, are becoming more and more important industrially because of their unique properties. Polysiloxanes that contain Si[BOND]O[BOND]Si linkage in their structure are most commonly prepared by ring-opening polymerization of cyclic siloxanes. The monomer for this process is prepared by the ‘Direct Process’. The polysiloxanes are hydrophobic despite having polar Si[BOND]O bonds in their structures. They possess highly flexible structures with large Si[BOND]O[BOND]Si bond angles. They are chemically inert and have good thermal stability, low viscosity, and good gas permeability. These polymers and related copolymers find use in a variety of fields as silicone fluids, elastomers, and resins. Polysilanes consisting of chains exclusively made up of silicon atoms are most commonly prepared by Wurtz coupling reaction. through sodium condensation of dichlorosilanes. The most interesting aspect of their properties is σ-electron delocalization, which gives rise to many interesting photochemical and photophysical effects like thermochromism, solvatochromism, and ionochromism. These polymers find use in preparation of silicon carbide and as photoresists, photoinitiators, and hole conductors in electrophotography. In this article, the history, synthesis, properties, and application of polysiloxane and polysilane polymers have been reviewed.

Keywords:

  • silicone;
  • polysiloxane;
  • polysilane;
  • direct process;
  • hydrosilation;
  • thermochromism