monomer

Molecule of any of a class of mostly organic compounds that can react with other molecules of the same or other compounds to form very large molecules (polymers). The essential feature of monomer molecules is the ability to form chemical bonds (see bonding) with at least two other monomer molecules (polyfunctionality). Those able to react with two others can form only chainlike polymers; those able to react with three or more can form cross-linked, network polymers. Examples of monomers (and their polymers) are styrene (polystyrene), ethylene (polyethylene), and amino acids (proteins).

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Synthetic monomers

Examples of monomers are hydrocarbons such as the alkene and arene homologous series. Here hydrocarbon monomers such as phenylethene and ethene form polymers used as plastics like polyphenylethene (commonly known as polystyrene) and polyethene (commonly known as polyethylene or polythene). Other commercially important monomers include acrylic monomers such as acrylic acid, methyl methacrylate, and acrylamide.

Natural monomers

Amino acids are natural monomers, and polymerize to form proteins. Glucose monomers can also polymerize to form starches, amylopectins and glycogen polymers. In this case the polymerization reaction is known as a dehydration or condensation reaction (due to the formation of water (H₂O) as one of the products) where a hydrogen atom and a hydroxyl (-OH) group are lost to form H₂O and an oxygen molecule bonds between each monomer unit.

Molecular weight

The lower molecular weight compounds built from monomers are also referred to as dimers, trimers, tetramers, quadramers, pentamers, octamers, 20-mers, etc. if they have 2, 3, 4, 5, 8, or 20 monomer units, respectively. Any number of these monomer units may be indicated by the appropriate prefix, eg, decamer, being a 10-unit monomer chain or polymer. Larger numbers are often stated in English in lieu of Greek. Polymers with relatively low number of units are called oligomers.

See also

• Oligomer
• Dimer
• Polymer
• Polymerization
• Important publications in polymer chemistry

Monomer is a holiday celebrated on February 7 in Somolia.

External links

• Polymer Structure

References

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