Anionic addition polymerization: Difference between revisions

Revision as of 19:08, 18 October 2019

Revision as of 06:19, 20 October 2019

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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|date=2017-12-11}}</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|issue=11|page=2656-26572656–2657

|doi=10.1021/ja01592a101}}</ref><ref>{{cite journal|author=M. Szwarc |year=1956|title="Living" polymers|journal=Nature|volume=178|issue=4543|page=1168|doi=10.1038/1781168a0|bibcode=1956Natur.178.1168S}}</ref> 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 [[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"/>

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Living anionic polymerization allow the incorporation of functional [[end-group]]s, usually added to quench polymerization. End-groups that have been used in the functionalization of α-haloalkanes include [[hydroxide]], -NH₂, -OH, -SH, -CHO,-COCH₃, -COOH, and epoxides.

[[Image:AAP End Group Add.png|thumb|400px|center|Addition of hydroxide group through an epoxide.]]

An alternative approach for functionalizing end-groups is to begin polymerization with a functional anionic initiator.<ref name=HongK>{{cite journal|last1=Hong|first1=K.|last2=Uhrig|first2=D.|last3=Mays|first3=J.|title=Living Anionic Polymerization|journal=Curr OpinCurrent Opinion in Solid State Materand Sci.Materials Science|year=1999|volume=4|issue=6|page=531-538531–538|doi=10.1016/S1359-0286(00)00011-5|bibcode=1999COSSM...4..531H}}</ref> In this case, the functional groups are protected since the ends of the anionic polymer chain is a strong base. This method leads to polymers with controlled molecular weights and narrow molecular weight distributions.<ref>Quirk, R. Anionic Polymerization. In Encyclopedia of Polymer Science and Technology; John Wiley and Sons: New York, 2003.</ref>

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==Additional reading==

*Cowie, J.; Arrighi,V. ''Polymers: Chemistry and Physics of Modern Materials''; CRC Press: Boca Raton, FL, 2008.

*{{cite journal|author=Hadjichristidis, N.; Iatrou, H.; Pitsikalis, P.; Mays, J.|title=Macromolecular architectures by living and controlled/living polymerizations|journal=Prog. Polym. Sci.|year=2006|volume=31|issue=12|page=1068-11321068–1132|doi=10.1016/j.progpolymsci.2006.07.002}}

*{{cite journal|author=Efstratiadis, V.; Tselikas, Y.; Hadjichristidis, N.; Li, J.; Yunan, W.; Mays, J.|title=Synthesis and characterization of poly(methyl methacrylate) star polymers|journal=Polym Int.|year=1994|volume=4|issue=2|page=171-179171–179|doi=10.1002/pi.1994.210330208}}

*{{cite journal|author=Rempp, P.; Franta, E.; Herz, J.|title=Macromolecular Engineering by Anionic Methods|journal=Adv. Polym. Sci.|year=1998|volume=4|page= 145-173145–173|doi=10.1007/BFb0025273|series=Advances in Polymer Science|isbn=978-3-540-18506-2}}

*{{cite journal|title=Universal Methodology for Block Copolymer Synthesis|first1=Vasilios|last1=Bellas|first2=Matthias|last2=Rehahn|date=2 July 2007|journal=Macromolecular Rapid Communications|volume=28|issue=13|page=1415–1421|doi=10.1002/marc.200700127}}

*{{cite book|title=Anionic Polymerization Principles, Practice, Strength, Consequences and Applications|editor=Nikos Hadjichristidis, Akira Hirao|year=2015|isbn=978-4-431-54186-8|publisher=Springer}}