Inorganic polymer
Encyclopedia
Inorganic polymers are polymer
s with a skeletal structure that does not include carbon
atoms. Polymers containing inorganic and organic components are named hybrid polymers. 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, mica
and feldspar
with other elements.
The inorganic sulfur
-nitrogen
polymer polythiazyl
, (SN)x, is, highly unusually, a metallic superconducting polymer below 0.26 K.
Polymerization
Inorganic polymers are formed, like organic polymers, by:
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
s with a skeletal structure that does not include carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
atoms. Polymers containing inorganic and organic components are named hybrid polymers. One of the best known examples is polydimethylsiloxane
Polydimethylsiloxane
Polydimethylsiloxane belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones. PDMS is the most widely used silicon-based organic polymer, and is particularly known for its unusual rheological properties. PDMS is optically clear, and, in general, is...
, otherwise known commonly as silicone rubber
Silicone rubber
Silicone rubber is an elastomer composed of silicone—itself a polymer—containing silicon together with carbon, hydrogen, and oxygen. Silicone rubbers are widely used in industry, and there are multiple formulations...
. It has a repeat unit
Repeat unit
An essential concept which defines polymer structure, the repeat unit or repeating unit is a part of a polymer chain whose repetition would produce the complete polymer by linking the repeat units together successively along the chain, like the beads of a necklace.A repeat unit is sometimes called...
based on silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
:
—[O-Si(CH3)2]n—
Silicon and oxygen also occur widely in a range of inorganic minerals, including silica, mica
Mica
The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...
and feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
with other elements.
The inorganic sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
-nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
polymer polythiazyl
Polythiazyl
Polythiazyl , x, was the first conducting inorganic polymer. In addition to being an electrical conductor, it was also found to be a superconductor at very low temperatures .-Structure and bonding:...
, (SN)x, is, highly unusually, a metallic superconducting polymer below 0.26 K.
Examples
- Homochain polymers with one kind of atom in the main chain:
- SiliconSiliconSilicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
-Silicon: Polysilanes; - GermaniumGermaniumGermanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. The isolated element is a semiconductor, with an appearance most similar to elemental silicon....
-germanium: Polygermanes; - TinTinTin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
-tin: PolystannanePolystannanePolystannanes are organotin compounds with the formula n. These polymers have been of intermitant academic interest; they are unusual because heavy elements comprise the backbone...
s.
- Silicon
- Heterochain polymers with more than one type of atom in the main chain, mostly two types of atoms alternate along the main chain:
- BoronBoronBoron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
-nitrogenNitrogenNitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
: Polyborazylenes; - Silicon-OxygenOxygenOxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
: Polysiloxanes like the PolydimethylsiloxanePolydimethylsiloxanePolydimethylsiloxane belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones. PDMS is the most widely used silicon-based organic polymer, and is particularly known for its unusual rheological properties. PDMS is optically clear, and, in general, is...
(PDMS), Polymethylhydrosiloxane (PMHS) and polydiphenylsiloxane; - Silicon-nitrogen: PolysilazanePolysilazanePolysilazanes are polymers in which silicon and nitrogen atoms alternate to form the basic backbone. Since each silicon atom is bound to two separate nitrogen atoms and each nitrogen atom to two silicon atoms, both chains and rings of the formula [R1R2Si–NR3]n occur. R1-R3 can be hydrogen atoms or...
s like Perhydridopolysilazane PHPS - PhosphorusPhosphorusPhosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
-nitrogen: PolyphosphazenePolyphosphazenePolyphosphazenes are a class of inorganic polymers with the repeat unit . The substituents R,R' are usually alkoxy, amino, , or halogens ....
s and their precursor the Poly(dichlorophosphazene)Poly(dichlorophosphazene)poly, also called dichlorophosphazine polymer or phosphonitrilechloride polymer, is chemical compound with formula n...
; - SulfurSulfurSulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
-nitrogen: PolythiazylPolythiazylPolythiazyl , x, was the first conducting inorganic polymer. In addition to being an electrical conductor, it was also found to be a superconductor at very low temperatures .-Structure and bonding:...
s.
- Boron
- Sulfur: PolysulfidePolysulfidePolysulfides are a class of chemical compounds containing chains of sulfur atoms. There are two main classes of polysulfides: anions and organic polysulfides. Anions have the general formula Sn2−. These anions are the conjugate bases of the hydrogen polysulfides H2nSn...
s.
PolymerizationPolymerizationIn polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
Inorganic polymers are formed, like organic polymers, by:
- Step-growth polymerizationStep-growth polymerizationStep-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers. Many naturally occurring and some synthetic polymers are produced by step-growth...
: Polysiloxanes; - Chain-growth polymerization: Polysilanes;
- Ring-opening polymerizationRing-opening polymerizationIn polymer chemistry, ring-opening polymerization is a form of chain-growth polymerization, in which the terminal end of a polymer acts as a reactive center, where further cyclic monomers join to form a larger polymer chain through ionic propagation...
: Poly(dichlorophosphazene).