Anionic addition polymerization

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Anionic addition polymerization

An anionic addition polymerization of vinyl

Vinyl

A vinyl compound is any organic compound that contains a vinyl group , −CarbonHydrogenCovalent bondCH2. These are derivatives of ethene, CH2=CH2, with one hydrogen atom replaced with some other group....
monomers is an addition polymerization

Addition polymerization

Addition polymerisation, also called polyaddition or chain growth polymerisation, is a polymerisation technique where Unsaturated compound monomer molecules add on to a growing polymer chain one at a time ....
initiated by a strong base

Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
and anion, such as an alkali

Alkali metal

The alkali metals are a chemical series of chemical elements comprising Periodic table group of the periodic table: lithium , sodium , potassium , rubidium , caesium , and francium ....
amide

Amide

In chemistry, an amide is one of three kinds of compounds:* the organic chemistry functional group characterized by a carbonyl group linked to a nitrogen atom , or a compound that contains this functional group ; or...
, or an organometallic compound, such as n-butyllithium

N-Butyllithium

n-Butyllithium is the most prominent organolithium reagent. It enjoys wide use as a polymerisation initiator in the production of elastomers such as polybutadiene or Styrene-butadiene....
.

A nucleophilic carbanion

Carbanion

A carbanion is an anion in which carbon has an unshared pair of electrons and bears a negative charge usually with three substituents for a total of eight valence electrons ....
is formed containing an unshared pair of electrons.

Confronted with a carbon molecule with a terminal double bond, such as ethene and a wide variety of monomer

Monomer

A monomer is a small molecule that may become Chemistry chemical bonding to other monomers to form a polymer....
vinyl

Vinyl

Styrene

Styrene, also known as vinyl benzene as well as many other names , is an organic compound with the chemical formula C6H5CH=CH2....
or acrylonitrile

Acrylonitrile

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An anionic addition polymerization of vinyl

Vinyl

Addition polymerization

Base (chemistry)

Alkali metal

The alkali metals are a chemical series of chemical elements comprising Periodic table group of the periodic table: lithium , sodium , potassium , rubidium , caesium , and francium ....
amide

Amide

N-Butyllithium

Carbanion

Monomer

A monomer is a small molecule that may become Chemistry chemical bonding to other monomers to form a polymer....
vinyl

Vinyl

Styrene

Styrene, also known as vinyl benzene as well as many other names , is an organic compound with the chemical formula C6H5CH=CH2....
or acrylonitrile

Acrylonitrile

Acrylonitrile is the chemical compound with the formula CH2CHCN. This pungent-smelling colorless liquid often appears yellow due to impurities....
, a conjugate addition occurs between the terminal carbon atom of the carbanion and the first carbon atom of the C = C bond. The unshared pair of electrons moves to the other carbon atom of C = C bond. A new but longer carbanion is formed that will react likewise.

A rapid chain-reaction polymerization reaction follows and a macromolecule

Macromolecule

The term macromolecule by definition implies "large molecule". In the context of biochemistry, the term may be applied to the four conventional biopolymers , as well as non-polymeric molecules with large molecular mass such as macrocycles....
is formed.

The reaction only stops when all monomer

Monomer

A monomer is a small molecule that may become Chemistry chemical bonding to other monomers to form a polymer....
is consumed or when another reaction occurs with an impurity or a molecule that is not part of the polymerization process.

Vinyl polymers are widely used, such as synthetic elastomer

Elastomer

An elastomer is a polymer with the property of elasticity. The term, which is derived from elastic polymer, is often used interchangeably with the term rubber, and is preferred when referring to vulcanization....
s, acrylic glass

Acrylic glass

Poly poly is a thermoplastic and transparency plastic. Chemically, it is the synthetic polymer of methyl methacrylate. It is sold by the trade names Plexiglas, Vitroflex, Limacryl, 'R-Cast, 'Per-Clax, 'Perspex, 'Plazcryl, 'Acrylex, 'Acrylite, 'Acrylplast, 'Altuglas, 'Polycast...
and polystyrene
Polystyrene

Polystyrene , sometimes abbreviated PS, is an Aromaticity polymer made from the aromatic monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry....
.

CH₃CH₂CH₂CH₂Li ? CH₃CH₂CH₂CH₂: ⁻ Li⁺

n-butyllithium ? n-butyl carbanion

CH₃CH₂CH₂CH₂: ⁻ Li⁺ + CH₂=CH₂ ? CH₃CH₂CH₂CH₂CH₂CH₂: ⁻ Li⁺

n-butyl carbanion + ethene ? n-hexyl carbanion

Anionic addition polymerization is not confined to vinyl compounds. It equally occurs when 1,2-epoxyethane (commonly known as ethylene oxide
Ethylene oxide

Ethylene oxide is the organic compound with the chemical formula C2H4O. This colorless flammable gas with a faintly sweet odor is the simplest epoxide, a three-membered ring consisting of two carbon and one oxygen atom....
) reacts with a small amount of a base
Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
, such as sodium methoxide
Methoxide

Methoxide is an organic salt, and the simplest alkoxide.In Organic chemistry, the methoxide ion has a formula of CH3O- and is the conjugate base of methanol....
. It turns, through polymerization , into a polyether of high molecular weight.