Inorganic Polymers

Inorganic polymers are polymers with a skeletal structure that does not include carbon atoms.^[1] Polymers containing inorganic and organic components are named hybrid polymers.^[2] One of the best known examples is polydimethylsiloxane, otherwise known commonly as silicone rubber. It has a repeat unit based on silicon and oxygen:

—[O-Si(CH₃)₂]_n—

Silicon and oxygen also occur widely in a range of inorganic minerals, including silica, micaand feldspar with other elements.

The inorganic sulfur-nitrogen polymer polythiazyl, (SN)_x, is, highly unusual, a metallic superconducting polymer below 0.26 K.^[3]

Inorganic polymers with tunable or responsive properties are called smart inorganic polymers. A special class of inorganic polymers are geopolymers which my be anthropogenic or naturally occurring.

Examples

• Homochain polymers with one kind of atom in the main chain:
  • Silicon-silicon: polysilanes; precursors to fibrous silicon carbide
  • Germanium-germanium: polygermanes
  • Tin-tin: polystannanes
• Heterochain polymers with more than one type of atom in the main chain, mostly two types of atoms alternate along the main chain, ranked by atomic weight of in-chain elements:^[4]
  • Boron-nitrogen: polyborazylenes
  • Silicon-oxygen: polysiloxanes like the polydimethylsiloxane (PDMS), polymethylhydrosiloxane (PMHS) and polydiphenylsiloxane
  • Silicon-nitrogen: polysilazanes like perhydridopolysilazane PHPS
  • Phosphorus-nitrogen: polyphosphazenes and their precursor the poly(dichlorophosphazene)
  • Phosphorus-oxygen: polyphosphates, which occur naturally and are widely used commercially.
  • Sulfur-nitrogen: polythiazyls
• Sulfur: polysulfides

Polymerisation

Inorganic polymers are formed, like organic polymers, by:

• Step-growth polymerization: Polysiloxanes;
• Chain-growth polymerization: Polysilanes;
• Ring-opening polymerization: Poly(dichlorophosphazene).

References

1. ^ http://goldbook.iupac.org/IT07515.html
2. ^ http://goldbook.iupac.org/HT07556.html
3. ^ M. M. Labes; P. Love; L. F. Nichols (1979). "Polysulfur nitride - a metallic, superconducting polymer". Chem. Rev. 79 (1): 1–15. doi:10.1021/cr60317a002.
4. ^ Mark, J. E.; Allcock, H. R.; West, R. “Inorganic Polymers” Prentice Hall, Englewood, NJ: 1992. ISBN 0-13-465881-7.

Wikipedia