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In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. 〔Young, R. J. (1987) ''Introduction to Polymers'', Chapman & Hall ISBN 0-412-22170-5〕〔(International Union of Pure and Applied Chemistry, ''et al.'' (2000) ''IUPAC Gold Book'', Polymerization )〕〔Clayden, J., Greeves, N. and Warren, S. (2000). (''Organic chemistry'' ), Oxford University Press ISBN 0198503466 pp. 1450–1466〕 There are many forms of polymerization and different systems exist to categorize them. ==Introduction== In chemical compounds, polymerization occurs via a variety of reaction mechanisms that vary in complexity due to functional groups present in reacting compounds〔 and their inherent steric effects. In more straightforward polymerization, alkenes, which are relatively stable due to bonding between carbon atoms, form polymers through relatively simple radical reactions; in contrast, more complex reactions such as those that involve substitution at the carbonyl group require more complex synthesis due to the way in which reacting molecules polymerize.〔 As alkenes can be formed in somewhat straightforward reaction mechanisms, they form useful compounds such as polyethylene and polyvinyl chloride (PVC) when undergoing radical reactions,〔 which are produced in high tonnages each year〔 due to their usefulness in manufacturing processes of commercial products, such as piping, insulation and packaging. In general, polymers such as PVC are referred to as "homopolymers," as they consist of repeated long chains or structures of the same monomer unit, whereas polymers that consist of more than one molecule are referred to as copolymers (or co-polymers).〔Cowie, J.M.G. (1991) ''Polymers: Chemistry and Physics of Modern Materials'', Chapman and Hall, p. 4 ISBN 0849398134〕 Other monomer units, such as formaldehyde hydrates or simple aldehydes, are able to polymerize themselves at quite low temperatures (ca. −80 °C) to form trimers;〔 molecules consisting of 3 monomer units, which can cyclize to form ring cyclic structures, or undergo further reactions to form tetramers,〔 or 4 monomer-unit compounds. Further compounds either being referred to as oligomers〔 in smaller molecules. Generally, because formaldehyde is an exceptionally reactive electrophile it allows nucleophillic addition of hemiacetal intermediates, which are in general short-lived and relatively unstable "mid-stage" compounds that react with other molecules present to form more stable polymeric compounds. Polymerization that is not sufficiently moderated and proceeds at a fast rate can be very hazardous. This phenomenon is known as hazardous polymerization and can cause fires and explosions. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Polymerization」の詳細全文を読む スポンサード リンク
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