Anionic chain polymerization commercial applications

Low molecular weight polybutadienes of various mixed microstructures are prepared281 commercially via an anionic chain transfer process. These polymerizations use toluene as the solvent and transfer agent and lithium as the counter ion. The transfer reactions is promoted by the use of diamines, e.g., tetramethylethylene-diamine, or potassium t-butoxide. The preparation, modification, and applications of these materials has been described by Luxton281). 

In anionic solution systems the feed stocks are typically dried over various types of dessicants because the systems are sensitive to water contamination. When using continuous anionic solution polymerization systems, it is necessary to employ low (ppm) concentrations of a chain-transfer agent in order to discourage gelation and fouling 1,2-butadiene is often used for this purpose in commercial applications. Alkyl-lithium-initiated polybutadiene is less prone to contain gel and does not contain the heavy metal catalyst residues associated with Ziegler-Natta catalyzed products. 

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