Editing Monomer

{{short description|Molecule which reacts with other monomers to form a polymer}}

A '''monomer''' ({{IPAc-en|ˈ|m|ɒ|n|ə|m|ər}} {{respell|MON|ə|mər}}; ''[[wikt:mono-|mono-]]'', "one" + ''[[wikt:-mer|-mer]]'', "part") is a [[molecule]] that can [[chemical reaction|react]] together with other monomer molecules to form a larger [[polymer]] chain or two- or three-dimensional network in a process called [[polymerization]].<ref>Young, R. J. (1987) ''Introduction to Polymers'', Chapman & Hall {{ISBN|0-412-22170-5}}</ref><ref>[http://goldbook.iupac.org/P04740.html International Union of Pure and Applied Chemistry, ''et al.'' (2000) ''IUPAC Gold Book'', '''Polymerization''']</ref><ref name="clayden_organic">{{Clayden|pages=1450–1466}}</ref>{{Quote box
| title = [[International Union of Pure and Applied Chemistry|IUPAC]] definition
| quote = '''Monomer molecule''': A molecule which can undergo polymerization, thereby contributing constitutional units to the essential structure of a [[macromolecule]].<ref>{{cite journal|title=Glossary of basic terms in polymer science (IUPAC Recommendations 1996)|journal=[[Pure and Applied Chemistry]]|year=1996|volume=68|issue=12|pages=2287–2311|doi=10.1351/pac199668122287|url=http://pac.iupac.org/publications/pac/pdf/1996/pdf/6812x2287.html|doi-access=free|last1=Jenkins|first1=A. D.|last2=Kratochvíl|first2=P.|last3=Stepto|first3=R. F. T.|last4=Suter|first4=U. W.}}</ref>
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==Classification==
[[Chemistry]] classifies monomers by type, and two broad classes based on the type of [[polymer]] they form.

By type:
* natural vs synthetic, e.g. [[glycine]] vs [[caprolactam]], respectively
* polar vs nonpolar, e.g. [[vinyl acetate]] vs [[ethylene]], respectively
* cyclic vs linear, e.g. [[ethylene oxide]] vs [[ethylene glycol]], respectively

By type of polymer they form:
* those that participate in [[condensation polymerization]]
* those that participate in [[addition polymerization]]

Differing [[stoichiometry]]<ref>{{cite book|title=An Introduction to Polymer Chemistry|publisher=Pergamon Press|year= 1967|author=D. Margerison |author2=G. C. East |author3=J. E. Spice |isbn=978-0-08-011891-8}}</ref>  causes each class to create its respective form of polymer.

:[[Image:Condensation polymerization diacid diamine.svg|thumb|centre|600px|This nylon is formed by [[condensation polymerization]] of two monomers, yielding water]]

The [[polymerization]] of one kind of monomer gives a [[polymer#Monomers and repeat units|homopolymer]].  Many polymers are [[copolymers]], meaning that they are derived from two different monomers.  In the case of condensation polymerizations, the ratio of [[comonomer]]s is usually 1:1.  For example, the formation of many nylons requires equal amounts of a [[dicarboxylic acid]] and [[diamine]].  In the case of addition polymerizations, the comonomer content is often only a few percent.  For example, small amounts of 1-octene monomer are copolymerized with ethylene to give specialized polyethylene.

==Synthetic monomers==
* [[Ethylene]] gas (H<sub>2</sub>C=CH<sub>2</sub>) is the monomer for [[polyethylene]].
* Other modified ethylene derivatives include:
**[[tetrafluoroethylene]] (F<sub>2</sub>C=CF<sub>2</sub>) which leads to [[Teflon]]
**[[vinyl chloride]] (H<sub>2</sub>C=CHCl) which leads to [[PVC]]
**[[styrene]] (C<sub>6</sub>H<sub>5</sub>CH=CH<sub>2</sub>) which leads to [[polystyrene]]
* [[Epoxide]] monomers may be cross linked with themselves, or with the addition of a co-reactant, to form [[epoxy]]
* [[Bisphenol A|BPA]] is the monomer precursor for [[polycarbonate]]
* [[Terephthalic acid]] is a comonomer that, with ethylene glycol, forms [[polyethylene terephthalate]].
* [[Dimethylsilicon dichloride]] is a monomer that, upon hydrolysis, gives [[polydimethylsiloxane]].
* [[Ethyl methacrylate]] is an [[Acrylate polymer#Monomers|acrylic monomer]] that, when combined with an acrylic polymer, catalyzes and forms an acrylate plastic used to create artificial nail extensions

==Biopolymers==
The term "monomeric [[protein]]" may also be used to describe one of the proteins making up a [[multiprotein complex]].<ref>Bruce Alberts, Alexander Johnson, Julian Lewis, Otin Raff, Keith Roberts, and Peter Walter, ''Molecular Biology of the Cell,'' 2008, Garland Science, {{ISBN|978-0-8153-4105-5}}.</ref>

==Natural monomers==
Some of the main [[biopolymer]]s are listed below:

===Amino acids===
For ''proteins'', the monomers are [[amino acid]]s. Polymerization occurs at [[ribosome]]s. Usually about 20 types of amino acid monomers are used to produce proteins. Hence proteins are not homopolymers.

===Nucleotides ===
For polynucleic acids ([[DNA]]/[[RNA]]), the monomers are [[nucleotide]]s, each of which is made of a [[pentose]] sugar, a nitrogenous base and a phosphate group.  Nucleotide monomers are found in the [[cell nucleus]].  Four types of nucleotide monomers are precursors to DNA and four different nucleotide monomers are precursors to RNA.

===Glucose and related sugars===
For carbohydrates, the monomers are monosaccharides. The most abundant natural monomer is [[glucose]], which is linked by [[glycosidic bonds]] into the polymers [[cellulose]], [[starch]], and [[glycogen]].<ref>{{Cite journal|url = https://www.academia.edu/5082714|title = Biomolecules: Classification and structural properties of carbohydrates|website = Academia.edu|last = Ebuengan|first = Kaye}}</ref>

===Isoprene===
[[Isoprene]] is a natural monomer that polymerizes to form a [[natural rubber]], most often ''cis-''1,4-polyisoprene, but also ''trans-''1,4-polymer.  [[Synthetic rubber]]s are often based on [[butadiene]], which is structurally related to isoprene.

==See also==
* [[Protein subunit]]
* [[List of publications in chemistry#Polymer chemistry|List of publications in polymer chemistry]]
* [[Prepolymer]]

==Notes==
{{Reflist}}

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[[Category:Monomers| ]]