In
polymer chemistry, vinyl polymers are a group of
polymers derived from substituted
vinyl
Vinyl may refer to:
Chemistry
* Polyvinyl chloride (PVC), a particular vinyl polymer
* Vinyl cation, a type of carbocation
* Vinyl group, a broad class of organic molecules in chemistry
* Vinyl polymer, a group of polymers derived from vinyl ...
()
monomers. Their
backbone
The backbone is the vertebral column of a vertebrate.
Arts, entertainment, and media Film
* ''Backbone'' (1923 film), a 1923 lost silent film starring Alfred Lunt
* ''Backbone'' (1975 film), a 1975 Yugoslavian drama directed by Vlatko Gilić
...
is an extended
alkane chain .
In popular usage, "vinyl" refers only to
polyvinyl chloride (PVC).
Examples
Vinyl polymers are the most common type of plastic. Important examples can be distinguished by the R group in the monomer H
2C=CHR:
*
Polyethylene R = H
*
polypropylene from
propylene, R = CH
3
*
Polystyrene is made from
styrene
Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...
, R = C
6H
5
*
Polyvinyl chloride (PVC) is made from
vinyl chloride, R= Cl
*
Polyvinyl acetate (PVAc) is made from
vinyl acetate
Vinyl acetate is an organic compound with the formula CH3CO2CH=CH2. This colorless liquid is the precursor to polyvinyl acetate and ethene-vinyl acetate copolymers, important industrial polymers.
Production
The worldwide production capacity of v ...
, R = O
2CCH
3
*
Polyacrylonitrile
Polyacrylonitrile (PAN), also known as polyvinyl cyanide and Creslan 61, is a synthetic, semicrystalline organic polymer resin, with the linear formula (C3H3N)n. Though it is thermoplastic, it does not melt under normal conditions. It degrades bef ...
is made from
acrylonitrile, R = CN
:
Production
Vinyl polymers are produced using catalysts.
Ziegler–Natta catalyst A Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, is a catalyst used in the synthesis of polymers of 1-alkenes ( alpha-olefins). Two broad classes of Ziegler–Natta catalysts are employed, distinguished by their solubility:
* ...
s are used commercially for production of polyethylene and polypropylene. Many are produced using radical initiators which are produced from
organic peroxides. Still others (poystyrene) are produced using anionic initiators such as
butyl lithium Butyllithium may refer to one of 5 isomeric organolithium reagents of which 3 are commonly used in chemical synthesis:
* ''n''-Butyllithium, abbreviated BuLi or nBuLi
* ''sec''-Butyllithium, abbreviated ''sec''-BuLi or sBuLi, has 2 stereoisomers, ...
.
An exception from the usual rules,
polyvinyl alcohol, )
n, is produced by hydrolysis of polyvinyl acetate. Vinyl alcohol is not sufficiently stable to undergo polymerization.
Structure
Vinyl polymers are subject of several structural variations, which greatly expands the range of polymers and their applications.
With the exception of polyethylene, vinyl polymers can arise from head-to-tail linking of monomers, head-to-head combined with tail-to-tail, or a mixture of those two patterns. Additionally the substituted carbon center in such polymers is
stereogenic
In stereochemistry, a stereocenter of a molecule is an atom (center), axis or plane that is the focus of stereoisomerism; that is, when having at least three different groups bound to the stereocenter, interchanging any two different groups cr ...
(a "chiral center"), with the result that the relative
absolute configuration
Absolute configuration refers to the spatial arrangement of atoms within a chiral molecular entity (or group) and its resultant stereochemical description. Absolute configuration is typically relevant in organic molecules, where carbon is bonde ...
s of these centers within a polymer can influence the properties of the polymer. This feature is called
tacticity
Tacticity (from el, τακτικός, taktikos, "relating to arrangement or order") is the relative stereochemistry of adjacent chiral centers within a macromolecule. The practical significance of tacticity rests on the effects on the physical ...
. The polymerization conditions and the catalysts affect tacticity.
Another major variation for vinyl polymers arises from the copolymerization of differing vinyl monomers. The simplest example is ethylene-propylene copolymer. The %
comonomer is yet another variation.
See also
*
Acrylate polymer
An acrylate polymer (also known as acrylic or polyacrylate) is any of a group of polymers prepared from acrylate monomers. These plastics are noted for their transparency, resistance to breakage, and elasticity.
Acrylate polymer is commonly use ...
References
{{Reflist
Organic polymers