Anionic addition polymerization: Difference between revisions

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== Monomer characteristics ==

Two broad classes of monomers are susceptible to anion-inducedanionic polymerization.<ref name="Quirk"/>

===Vinyl monomers===

Vinyl monomers have the formula CH₂=CHR, the most important are styrene (R = C₆H₅), butadiene (CH=CH₂), and isoprene (R = C(Me)=CH₂). A second major class of monomers are acrylate esters, such as [[acrylonitrile]], [[methacrylate]], [[cyanoacrylate]], and [[acrolein]]. Other vinyl monomers include [[vinylpyridine]], vinyl [[sulfone]], vinyl [[sulfoxide]], [[vinyl silane]]s.<ref name="Quirk"/>

[[ImageFile:Ex polar monomers.png|thumb|300px|right|Examples of polar monomers.]]

[[ImageFile:Example Vinyl monomer.png|thumb|200px|right|Examples of vinyl monomers.]]

===Cyclic monomers===

[[File:Wiki65656.tif|thumb|600px|center|The anionic ring-opening polymerization of ε-caprolactone, initiated by alkoxide.]]

[[file:Hexamethylcyclotrisiloxan.svg|thumb|140px|right|Hexamethylcyclotrisiloxane]] is a cyclic monomer that is susceptible to anionic polymerization to [[siloxane]] polymers.]]

Many cyclic compounds are susceptible to [[ring-opening polymerization]]. [[Epoxide]]s, cyclic tri[[siloxane]]s, some lactones, [[lactide]]s, [[cyclic carbonate]]s, and [[amino acid N-carboxyanhydride]]s.

In order for polymerization to occur with [[vinyl group|vinyl]] [[monomer]]s, the [[substituent]]s on the [[double bond]] must be able to stabilize a [[negative charge]]. Stabilization occurs through [[delocalization]] of the negative charge. Because of the nature of the [[carbanion]] propagating center, substituents that react with bases or nucleophiles either must not be present or be protected.<ref name="Quirk"/>