Anionic addition polymerization: Difference between revisions

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== History ==

[[File:ET-coupledStyrene.png|thumb|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.<ref>{{cite book|chapter=Ionic Polymerization|author=Sebastian Koltzenburg, Michael Maskos, Oskar Nuyken|title=Polymer Chemistry|isbn=978-3-662-49279-6|publisher=Springer}}</ref>]]

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.<ref>{{cite journal|title=Polymerization Initiated by Electron Transfer to Monomer. A New Method of Formation of Block Polymers|first1=M.|last1=Szwarc|first2=M.|last2= Levy|first3=R.|last3=Milkovich|journal=J. Am. Chem. Soc.|year=1956|volume=78|page=2656-2657

|doi=10.1021/ja01592a101}}</ref><ref>{{cite journal|author=M. Szwarc |year=1956|title="Living" polymers|journal=Nature|volume=178|page=1168|doi=10.1038/1781168a0}}</ref> The early work of [[Michael Szwarc]] and co – workers in 1956 was In one of the breakthrough events in the field of [[polymer science]], Szwarc learnedelucidated that the [[electron transfer]] betweenoccurred from [[radical anion]] of [[naphthalene]] and to[[styrene]]. in an [[aprotic solvent]] such as [[tetrahydrofuran]]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 [[chemical kinetics|kinetics]] and the [[thermodynamics]] of the process in considerable detail. At the same time, he explored the structure property relationship of the various [[ion pair]]s 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.<ref>Smid, J. Historical Perspectives on Living Anionic Polymerization. ''J. Polym. Sci. Part A.''; '''2002''', ''40'',pp. 2101-2107. [https://archive.today/20121012113202/http://www3.interscience.wiley.com/journal/94515609/abstract DOI=10.1002/pola.10286]</ref>

The use of [[alkali metals]] to initiate polymerization of 1,3-[[diene]]s led to the discovery by Stavely and co-workers at Firestone Tire and Rubber company of cis-1,4-[[polyisoprene]].<ref name=Odian>Odian, G. Ionic Chain Polymerization; In '' Principles of Polymerization''; Wiley-Interscience: Staten Island, New York, 2004, pp. 372-463.</ref> This sparked the development of commercial anionic polymerization processes that utilize alkyllithium initiatiors.<ref name="Quirk"/>