文档介绍：Anionic Polymerization
Initiator and Monomer
Mechanism
Living Polymer
ics
between Radical & Ionic
Polymerization
Overview
1877 ---- Waitz ring-openingly polymerized
ethylene oxide.
1949 --- Styrene and acrylic nitrile are polymerized in
liquid ammonia with potassium amide as a
initiator, which bring out a mechanism of the
anionic polymerization.
1952---- Quantitative ic studies were done.
1956 ---- Szwarc notified the cationic living polymer-
ization.
Polymers of specific structure, like ABA block copolymer, starshaped polymer and pectinate polymer, could be synthesized, meeting the aim of polymer molecular practice is realized, for example, the produce of liquid butadiene styrene rubber and butadiene styrene block copolymer SBS resin has been industrialized.
4·3·1 The Initiator and Monomer
Typical anionic polymerizable monomers : styrene, MMA and acrylic nitrile etc.
All types of monomers are π-π conjugated system or that with electron attracting group, makeing the density of electron cloud of double bond decline.
The anionic active center reacts with double bond by addition reaction.
Anionic polymerizable initiators are listed in the following table.
Common Intiator
Type of Initiator Molecular Formula or Examples
alkali metals suspension system Na suspends in THF or fluid chlorin
organic radical anion naphthalene natrium initiator
alkyl or aryl lithium reagent n-C4H9Li
Grignard eagent RMgX( R-alkyl or aryl group)
alkyl aluminium AlR3
4·3·1 The Initiator and Monomer
In these initiators:
The alkali metals suspension system is that in which melted alkali metal tiny beads disperse in an anic solvent;
Organic lithium reagent is prepared by metal lithium and alkyl halide in anic solvent;
Grignard reagent is prepared by the reaction of metal Mg and alkyl halide.
4·3·1 The Initiator and Monomer
The Radical anionic initiator,for example, naphthalene natrium must be prepared in an ether so