Monomer

Amonomer(⫽ˈmɒnəmər⫽MON-ə-mər;mono-,"one" +-mer,"part" ) is amoleculethat canreacttogether with other monomer molecules to form a largerpolymerchain or three-dimensional network in a process calledpolymerization.^[1]^[2]^[3]

IUPACdefinition

Monomer molecule:A molecule which can undergo polymerization, thereby contributing constitutional units to the essential structure of amacromolecule.^[4]

Classification[edit]

Chemistryclassifies monomers by type, and two broad classes based on the type ofpolymerthey form.

By type:

natural vs synthetic, e.g.glycinevscaprolactam,respectively
polar vs nonpolar, e.g.vinyl acetatevsethylene,respectively
cyclic vs linear, e.g.ethylene oxidevsethylene glycol,respectively

By type of polymer they form:

those that participate incondensation polymerization
those that participate inaddition polymerization

Differingstoichiometry^[5]causes each class to create its respective form of polymer.

Thepolymerizationof one kind of monomer gives ahomopolymer.Many polymers arecopolymers,meaning that they are derived from two different monomers. In the case of condensation polymerizations, the ratio ofcomonomersis usually 1:1. For example, the formation of many nylons requires equal amounts of adicarboxylic acidand 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[edit]

Ethylenegas (H₂C=CH₂) is the monomer forpolyethylene.
Other modified ethylene derivatives include:
- tetrafluoroethylene(F₂C=CF₂) which leads toTeflon
- vinyl chloride(H₂C=CHCl) which leads toPVC
- styrene(C₆H₅CH=CH₂) which leads topolystyrene
Epoxidemonomers may be cross linked with themselves, or with the addition of a co-reactant, to formepoxy
BPAis the monomer precursor forpolycarbonate
Terephthalic acidis a comonomer that, with ethylene glycol, formspolyethylene terephthalate.
Dimethylsilicon dichlorideis a monomer that, upon hydrolysis, givespolydimethylsiloxane.
Ethyl methacrylateis anacrylic monomerthat, when combined with an acrylic polymer, catalyzes and forms an acrylate plastic used to create artificial nail extensions

Biopolymers[edit]

The term "monomericprotein"may also be used to describe one of the proteins making up amultiprotein complex.^[6]

Natural monomers[edit]

Some of the mainbiopolymersare listed below:

Amino acids[edit]

Forproteins,the monomers areamino acids.Polymerization occurs atribosomes.Usually about 20 types of amino acid monomers are used to produce proteins. Hence proteins are not homopolymers.

Nucleotides[edit]

For polynucleic acids (DNA/RNA), the monomers arenucleotides,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[edit]

For carbohydrates, the monomers are monosaccharides. The most abundant natural monomer isglucose,which is linked byglycosidic bondsinto the polymerscellulose,starch,andglycogen.^[7]

Isoprene[edit]

Isopreneis a natural monomer that polymerizes to form anatural rubber,most oftencis-1,4-polyisoprene, but alsotrans-1,4-polymer.Synthetic rubbersare often based onbutadiene,which is structurally related to isoprene.

Notes[edit]

^Young, R. J. (1987)Introduction to Polymers,Chapman & HallISBN 0-412-22170-5
^International Union of Pure and Applied Chemistry,et al.(2000)IUPAC Gold Book,Polymerization
^Clayden, Jonathan;Greeves, Nick;Warren, Stuart;Wothers, Peter(2001).Organic Chemistry(1st ed.). Oxford University Press. pp. 1450–1466.ISBN 978-0-19-850346-0.
^Jenkins, A. D.; Kratochvíl, P.; Stepto, R. F. T.; Suter, U. W. (1996)."Glossary of basic terms in polymer science (IUPAC Recommendations 1996)".Pure and Applied Chemistry.68(12): 2287–2311.doi:10.1351/pac199668122287.
^D. Margerison; G. C. East; J. E. Spice (1967).An Introduction to Polymer Chemistry.Pergamon Press.ISBN 978-0-08-011891-8.
^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.
^Ebuengan, Kaye."Biomolecules: Classification and structural properties of carbohydrates".Academia.edu.

[1] Young, R. J. (1987)Introduction to Polymers,Chapman & HallISBN 0-412-22170-5

[2] International Union of Pure and Applied Chemistry,et al.(2000)IUPAC Gold Book,Polymerization

[clayden_organic-3] Clayden, Jonathan;Greeves, Nick;Warren, Stuart;Wothers, Peter(2001).Organic Chemistry(1st ed.). Oxford University Press. pp. 1450–1466.ISBN 978-0-19-850346-0.

[4] Jenkins, A. D.; Kratochvíl, P.; Stepto, R. F. T.; Suter, U. W. (1996)."Glossary of basic terms in polymer science (IUPAC Recommendations 1996)".Pure and Applied Chemistry.68(12): 2287–2311.doi:10.1351/pac199668122287.

[5] D. Margerison; G. C. East; J. E. Spice (1967).An Introduction to Polymer Chemistry.Pergamon Press.ISBN 978-0-08-011891-8.

[6] 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.

[7] Ebuengan, Kaye."Biomolecules: Classification and structural properties of carbohydrates".Academia.edu.

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