Polymerization

Article By:

Peetz, Ralf Chemistry Department, Center for Engineered Polymeric Materials, City University of New York/College of Staten Island, New York, New York.

Romack, T. J. Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina.

DeSimone, J. M. Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina.

Last reviewed:April 2019

DOI:https://doi.org/10.1036/1097-8542.535300

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• Polymerization, published June 2014:Download PDF Get Adobe Acrobat Reader

The repetitive linking of small molecules (monomers) to make larger molecules (polymers). In general, polymers are named after the small molecules from which they are made. For example, the gaseous monomer ethylene can be polymerized to make solid polyethylene. A polymer molecule may contain hundreds of thousands of repeat units, or monomers. Polymerization requires that each small molecule have at least two reaction points or functional groups. The polymerization of a monomer usually involves many steps. In each step, new bonds are formed, resulting in the extension and growth of the respective chain. Synthetic polymers are usually polydisperse; that is, in any given sample, the many polymer chains present will have varying lengths, while being of the same chemical composition. Consequently, the value describing a molecular weight or size of a polymer sample always refers to an average, such as a weight average or number average. Size and architecture of polymer molecules are of greatest importance to the polymer chemist, as they determine the ultimate material properties, and hence the necessary polymerization process. See also: Polymer

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