Condensation polymer

Condensation polymer

Condensation polymers are any kind of polymers formed through a condensation reaction, releasing small molecules as by-products such as water or methanol, as opposed to addition polymers which involve the reaction of unsaturated monomers. Types of condensation polymers include polyamides, polyacetals and polyesters.

Condensation polymerization, a form of step-growth polymerization, is a process by which two molecules join together, resulting loss of small molecules which is often water. The type of end product resulting from a condensation polymerization is dependent on the number of functional end groups of the monomer which can react.

Monomers with only one reactive group terminate a growing chain, and thus give end products with a lower molecular weight. Linear polymers are created using monomers with two reactive end groups and monomers with more than two end groups give three dimensional polymers which are crosslinked.

Dehydration synthesis often involves joining monomers with an -OH (hydroxyl) group and a freely ionized -H on either end (such as a hydrogen from the -NH2 in nylon or proteins). Normally, two or more different monomers are used in the reaction. The bonds between the hydroxyl group, the hydrogen atom and their respective atoms break forming water from the hydroxyl and hydrogen, and the polymer.

Polyester is created through ester linkages between monomers, which involve the functional groups carboxyl and hydroxyl (an organic acid and an alcohol monomer).

Nylon is another common condensation polymer. It can be manufactured by reacting di-amines with carboxyl derivatives. In this example the derivative is a di-carboxylic acid, but di-acyl chlorides are also used. Another approach used is the reaction of di-functional monomers, with one amine and one carboxylic acid group on the same molecule:

General chemical structure of one type of condensation polymer

The carboxylic acids and amines link to form peptide bonds, also known as amide groups. Proteins are condensation polymers made from amino acid monomers. Carbohydrates are also condensation polymers made from sugar monomers such as glucose and galactose.

Condensation polymerization is occasionally used to form simple hydrocarbons. This method, however, is expensive and inefficient, so the addition polymer of ethene (polyethylene) is generally used.

Condensation polymers, unlike addition polymers, may be biodegradable. The peptide or ester bonds between monomers can be hydrolysed by acid catalysts or bacterial enzymes breaking the polymer chain into smaller pieces.

The most commonly known condensation polymers are proteins, fabrics such as nylon, silk, or polyester.

See also


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • condensation polymer — a compound formed by the repeated reaction of smaller molecules, involving at the same time the elimination of water or other simple compound (e.g., nylon) …   Medical dictionary

  • Polymer degradation — is a change in the properties tensile strength, colour, shape, etc of a polymer or polymer based product under the influence of one or more environmental factors such as heat, light or chemicals. These changes are usually undesirable, such as… …   Wikipedia

  • Condensation reaction — The condensation of two amino acids to form a peptide bond (red) with expulsion of water (blue) A condensation reaction is a chemical reaction in which two molecules or moieties (functional groups) combine to form one single molecule, together… …   Wikipedia

  • Polymer — Appearance of real linear polymer chains as recorded using an atomic force microscope on surface under liquid medium. Chain contour length for this polymer is 204 nm; thickness is 0.4 nm.[1] A polymer is a large molecule (macromolecule …   Wikipedia

  • Polymer-bonded explosive — A polymer bonded explosive, also called PBX or plastic bonded explosive, is an explosive material in which explosive powder is bound together in a matrix using small quantities (typically 5–10% by weight) of a synthetic polymer ( plastic ). Note… …   Wikipedia

  • polymer — /pol euh meuhr/, n. Chem. 1. a compound of high molecular weight derived either by the addition of many smaller molecules, as polyethylene, or by the condensation of many smaller molecules with the elimination of water, alcohol, or the like, as… …   Universalium

  • condensation polymerization — the formation of polymer macromolecules by an intermolecular reaction involving at least two monomer species, usually with the production of a by product of low molecular weight, such as water …   Mechanics glossary

  • polymer — pol•y•mer [[t]ˈpɒl ə mər[/t]] n. chem. a compound of high molecular weight derived either by the addition of many smaller molecules, as polyethylene, or by the condensation of many smaller molecules with the elimination of water, alcohol, or the… …   From formal English to slang

  • polymer — /ˈpɒləmə / (say poluhmuh) noun Chemistry 1. a compound of high molecular weight derived either by the addition of many smaller molecules of the same compound or by the condensation of many smaller molecules eliminating water, alcohol, etc. 2. any …  

  • Addition polymer — An addition polymer is a polymer which is formed by an addition reaction, where many monomers bond together via rearrangement of bonds without the loss of any atom or molecule. This is in contrast to a condensation polymer which is formed by a… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”