page_title: Anionic addition polymerization
section_title: History
hierarchical_section_title: Anionic addition polymerization / History
caption_attribution_description: English: Product of the reductive coupling of styrene, 1,4-dilithio-1,4-diphenylbutane
context_page_description: Anionic addition polymerization is a form of chain-growth polymerization or addition polymerization that involves the polymerization of monomers initiated with anions. The type of reaction has many manifestations, but traditionally vinyl monomers are used. Often anionic polymerization involves living polymerizations, which allows control of structure and composition.
context_section_description: As early as 1936, Karl Ziegler proposed that anionic polymerization of styrene and butadiene by consecutive addition of monomer to an alkyl lithium initiator occurred without chain transfer or termination. Twenty years later, living polymerization was demonstrated by Szwarc and coworkers. In one of the breakthrough events in the field of polymer science, Szwarc elucidated that electron transfer occurred from radical anion of naphthalene to styrene. The results in the formation of a dianion (or equivalently disodio-) species, which rapidly added styrene to form a "two – ended living polymer."  An important aspect of his work, Szwarc employed the aprotic solvent tetrahydrofuran. Being a physical chemist, Szwarc elucidated the kinetics and the thermodynamics of the process in considerable detail. At the same time, he explored the structure property relationship of the various ion pairs and radical ions involved. This work provided the foundations for the rational synthesis of polymers with control over molecular weight, molecular weight distribution, and the architecture of the polymer.
  The use of alkali metals to initiate polymerization of 1,3-dienes led to the discovery by Stavely and co-workers at Firestone Tire and Rubber company of cis-1,4-polyisoprene. This sparked the development of commercial anionic polymerization processes that utilize alkyllithium initiatiors.
caption: Product of the reductive coupling of styrene with lithium, 1,4-dilithio-1,4-diphenylbutane. In the original work, Szwarc studied the analogous disodium compound.[5]
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