Polymerization Processes

Polymerization is a reaction where monomers are converted into a polymer. There are two types of polymerization reactions: Step-Growth Polymerization and Chain Polymerization. Step-Growth Polymerization applies to monomers with functional groups such as -COOH, -COOR, -COOOC-, -COCl, -OH, -NH2, -CHO, and -NCO. Chain Polymerization applies to monomers having double bonds or ring structure. The polymerization of a given monomer may proceed by the free radical, anionic, or cationic mechanism, depending on the chemical structure of the monomer. Both classes of reaction can lead to the formation of either linear polymers or branched polymers. Whether the polymer is of linear or branched chains only depends on the number of reactive entities per monomer. The degree or extent of polymerization can be expressed in terms of number average molecular weight (MWN) and weight average molecular weight (MWW). The Ziegler-Natta polymerization model is applicable to processes that utilize coordination catalysts for the production of stereo specific polymers.