A monomer ( ; ''

mono- Numeral or number prefixes are prefixes derived from numerals or occasionally other numbers. In English and many other languages, they are used to coin numerous series of words. For example: * triangle, quadrilateral, pentagon, hexagon, oc ...

'', "one" + '' -mer'', "part") is a

molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

that can react together with other monomer molecules to form a larger

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

chain or two- or three-dimensional network in a process called polymerization.

Classification

Chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

classifies monomers by type, and two broad classes based on the type of

they form. By type: * natural vs synthetic, e.g.

glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (G ...

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 causes each class to create its respective form of polymer. : 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

* 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 Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate ester, carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, toughness, tough materials, and some grades are optically transp ...

* 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

The term "monomeric

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

" may also be used to describe one of the proteins making up a multiprotein complex.

Natural monomers

Some of the main biopolymers are listed below:

Amino acids

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

For polynucleic acids ( DNA/

RNA Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...

), the monomers are

nucleotide Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...

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 The cell nucleus (; : nuclei) is a membrane-bound organelle found in eukaryote, eukaryotic cell (biology), cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have #Anucleated_cells, ...

. 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 Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...

, which is linked by glycosidic bonds into the polymers

cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

, starch, and glycogen.

Isoprene

Isoprene is a natural monomer that polymerizes to form a

natural rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene ...

, 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.

Notes

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