ketjupolimerointia

Ketjupolimerointi, also known as chain polymerization, is a fundamental process in polymer chemistry where monomers add sequentially to a growing polymer chain. This mechanism is characterized by three main stages: initiation, propagation, and termination. The initiation step involves the formation of an active center, which can be a radical, an anion, or a cation, that is capable of reacting with a monomer. In propagation, the active center attacks a monomer molecule, forming a new active center at the end of the growing chain. This process repeats, adding many monomer units to the chain. Termination occurs when the active center is destroyed, halting further chain growth. This can happen through various mechanisms, such as radical recombination or disproportionation in radical polymerization, or by the addition of a terminating agent. Ketjupolimerointi typically leads to polymers with a high molecular weight and often exhibits a relatively narrow molecular weight distribution. Common examples of polymers produced by ketjupolimerointi include polyethylene, polypropylene, polystyrene, and polyvinyl chloride. The specific type of active center dictates whether the polymerization is classified as free radical polymerization, anionic polymerization, or cationic polymerization, each with its own set of conditions and applications.