Polyvinylcarbazole
Chemical compound
From Wikipedia, the free encyclopedia
Polyvinylcarbazole (PVK) is a temperature-resistant[2] thermoplastic polymer produced by radical polymerization from the monomer N-vinylcarbazole. It is a photoconductive polymer and thus the basis for photorefractive polymers and organic light-emitting diodes.[3]
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| Names | |
|---|---|
| Other names
Poly(vinylcarbazole); Poly(N-vinylcarbazole); Poly(9-vinylcarbazole) | |
| Identifiers | |
CompTox Dashboard (EPA) |
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| Properties | |
| (C14H11N)n | |
| Melting point | > 320 °C[1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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History
Polyvinylcarbazole was discovered by the chemists Walter Reppe (1892-1969), Ernst Keyssner and Eugen Dorrer and patented by I.G. Farben in the USA in 1937.[4][1] PVK was the first polymer whose photoconductivity was known. Starting in the 1960s, further polymers of this kind were sought.[3]
Production
Polyvinylcarbazole is obtained from N-vinylcarbazole by radical polymerization in various ways. It can be produced by suspension polymerization at 180 °C with sodium chloride and potassium chromate as catalyst.[2] Alternatively, AIBN can also be used as a radical starter or a Ziegler-Natta catalyst.[1]
Properties
Physical properties
PVK can be used at temperatures of up to 160 - 170 °C and is therefore a temperature-resistant thermoplastic. The electrical conductivity changes depending on the illumination. For this reason, PVK is classified as a semiconductor or photoconductor. The polymer is extremely brittle, but the brittleness can be reduced by copolymerization with a little isoprene.[5]
Chemical properties
Polyvinylcarbazole is soluble in aromatic hydrocarbons, halogenated hydrocarbons and ketones.[1] It is resistant to acids, alkalis, polar solvents and aliphatic hydrocarbons.[2] The addition of PVK to other plastic masses increases their temperature resistance.
Use
Due to its high price and special properties, the use of PVK is limited to special areas.[2] It is used in insulation technology,[2] electrophotography (e.g. in copiers and laser printers),[3] for the fabrication of polymer photonic crystals,[6] for organic light-emitting diodes and photovoltaic devices.[1] In addition, PVK is a well researched component in photorefractive polymers and therefore plays an important role in holography. Another application is the production of cooking-proof copolymers with styrene.