How To Synthesize And Use Vinylcarbazole

Vinyl monomers are arguably the most broadly used monomer group in the world. Fundamentally vinyl monomers make up nearly everything we touch and use everyday, from Saran wrap/shrink-wrap to thick plastic chairs that we sit on and also for some of the cell phones that we are forced to carry by our bosses at work, and at home!

Digging deeper there are some subclasses of vinyl monomers that really impact our everyday life by allowing us some application performance that is very unique. For example, vinylcarbazole provides the backbone to some polymers which some of use would hate to live without, they form the basis of a lot of optoelectronics devices, which includes appliances such as photocopiers, laser printers and flat screen displays. The general information for vinylcarbazole is below:

Alternate names 9-vinyl-9H-carbazole; vinyl-9H-carbazole; N-vinylcarbazole CAS 1484-13-5 Molecular weight 193.24 g/mol Formula C14H11N

While there are several methods available to produce vinylcarbazole, the most accepted is an acetylenic addition to carbazole. This reaction is of course extremely dangerous because of the acetylation step. The acetylenic difficulty limits the number of companies who are qualified, or U.S. Federally permitted, to undertake this reaction. It is however available openly at specific chemical manufacturers.

As an individual compound, vinylcarbazole isn't particularly application heavy, but in a polymeric form this monomer is extremely interesting. By reacting vinylcarbazole in the presence of a radical initiator or gamma-radiation, poly(vinylcarbazole) can be produced. This polymer is sometimes referred to as 'PVK' (the K comes from the original German name for 'Karbazole'). Several articles discuss the polymer synthesis; a suggested example review would be R.C. Penwell and co-workers' review in the Journal of Polymer Science: Macromolecular Reviews, 2003, Vol. 13, Iss.1, Pg 63 to 160.

The most important property for poly(vinylcarbazole) is the photoconductivity and photoluminescence. These properties arise because of the significant aromatic and pi-electron content in the vinylcarbazole and PVK structures. When these types of structure are 'doped' (i.e., charges are intentional formed within the structure), the resulting structures have the ability to transport other charges (including electrons and photons) through the chain. A reasonable analogy here it to think about a boat being place on a river, a number of things can be placed in the boat and it gets carried to another place downstream. Well that occurs here and the movement of charge is the causes the 'conductivity', if the charge is a photon then you get photoconductivity.

A deeper discussion of photoconductivity and subsequent uses of PVK is beyond this article. However, the importance of this material is outlined by the consistent increase in scholarly articles and newly patented PVK materials.

by Chad DeBolt


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