ketjukasvu

Ketjukasvu, a Finnish term, translates to "chain growth" and is most commonly associated with polymer chemistry. It describes a polymerization mechanism where monomer units add sequentially to an active center. This active center can be a free radical, a cation, or an anion. The process involves three key stages: initiation, propagation, and termination. Initiation involves the creation of the initial active center, often by a radical initiator. Propagation is the step where monomer molecules repeatedly add to this active center, extending the polymer chain. Termination occurs when the active center is deactivated, halting chain growth. Different types of chain growth polymerization include free radical polymerization, cationic polymerization, and anionic polymerization, each with its own specific initiators and reaction conditions. This mechanism is fundamental to the production of many common plastics like polyethylene, polypropylene, and polystyrene. The rapid rate of chain growth is a defining characteristic, often leading to high molecular weight polymers in a relatively short time. The molecular weight distribution of polymers produced via chain growth can be controlled by careful selection of reaction parameters.