Monomer

Molecule which reacts with other monomers to form a polymer

A monomer (/ˈmɒnəmər/ MON-ə-mər; mono-, "one" + -mer, "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.[1][2][3]

IUPAC definition

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

## Classification

[edit]

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

This nylon is formed by condensation polymerization of two monomers, yielding water

The polymerization of one kind of monomer gives a homopolymer. Many polymers are copolymers, meaning that they are derived from two different monomers. In the case of condensation polymerizations, the ratio of comonomers 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

[edit]

* Ethylene gas (H2C=CH2) is the monomer for polyethylene.
* Other modified ethylene derivatives include:
* tetrafluoroethylene (F2C=CF2) which leads to Teflon
* vinyl chloride (H2C=CHCl) which leads to PVC
* styrene (C6H5CH=CH2) which leads to polystyrene
* Epoxide monomers may be cross linked with themselves, or with the addition of a co-reactant, to form epoxy
* 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 acrylic monomer that, when combined with an acrylic polymer, catalyzes and forms an acrylate plastic used to create artificial nail extensions

## Biopolymers

[edit]

The term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex.[6]

## Natural monomers

[edit]

Some of the main biopolymers are listed below:

### Amino acids

[edit]

For proteins, the monomers are amino acids. Polymerization occurs at ribosomes. 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 are nucleotides, 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 is glucose, which is linked by glycosidic bonds into the polymers cellulose, starch, and glycogen.[7]

### Isoprene

[edit]

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 rubbers are often based on butadiene, which is structurally related to isoprene.

## See also

[edit]

* Protein subunit
* List of publications in polymer chemistry
* Prepolymer

## Notes

[edit]

1. ^ Young, R. J. (1987) Introduction to Polymers, Chapman & Hall ISBN 0-412-22170-5
2. ^ International Union of Pure and Applied Chemistry, et al. (2000) IUPAC Gold Book, Polymerization
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.

Authority control databases: National |

* Czech Republic
* Israel

|