In addition polymerization, the reaction proceeds by the sequential addition of monomers to a growing polymer chain. This can occur through various mechanisms, including radical, ionic, and coordination polymerization. Each mechanism has its own characteristics and requirements, such as the need for initiators or catalysts.
Radical addition polymerization, for example, typically involves the use of initiators that produce radicals, which then react with monomers to start the polymerization process. The growing polymer chain can then add more monomers, and the process continues until the chain terminates.
Ionic addition polymerization, on the other hand, involves the use of initiators that produce ions, which then react with monomers to start the polymerization process. The growing polymer chain can then add more monomers, and the process continues until the chain terminates.
Coordination addition polymerization involves the use of transition metal complexes as catalysts. These catalysts can initiate the polymerization process and facilitate the addition of monomers to the growing polymer chain.
Addition polymerization has a wide range of applications, including the production of plastics, rubbers, and synthetic fibers. The process is also used in the synthesis of certain polymers used in pharmaceuticals and other specialized applications.
One of the key advantages of addition polymerization is its ability to produce polymers with well-defined molecular weights and narrow molecular weight distributions. This is because the process typically involves the addition of monomers to a growing polymer chain, rather than the random combination of smaller molecules, as in step-growth polymerization.
However, addition polymerization also has its challenges, such as the need for strict control of reaction conditions and the potential for side reactions that can affect the properties of the resulting polymer. Additionally, the process may require the use of toxic or expensive initiators or catalysts.