Additiopolymerointityyppejä

Additiopolymerointityyppejä refer to different mechanisms by which monomers add to a growing polymer chain without the loss of any atoms. The primary categories of addition polymerization are chain-growth polymerization and step-growth polymerization, though the latter is often discussed separately. In true addition polymerization, the reaction proceeds by the addition of monomers to an active center.

Chain-growth polymerization is characterized by three main mechanisms: free radical, cationic, and anionic polymerization. Free radical polymerization involves the formation of a free radical initiator, which then adds to a monomer to create a radicalic growing chain. This process continues as more monomers add to the radical end. Cationic polymerization is initiated by a cation, such as a carbocation, which attacks the electron-rich double bond of a monomer. Similarly, anionic polymerization is initiated by an anion, typically a carbanion, which attacks a monomer. In all chain-growth mechanisms, a small number of growing chains are present at any given time, and they grow rapidly to high molecular weights.

While sometimes grouped with addition polymerization, step-growth polymerization involves the reaction between functional groups of monomers, oligomers, and polymers, with the elimination of a small molecule like water or methanol. However, the term "additiopolymerointityyppejä" most commonly refers to the chain-growth mechanisms where monomers directly add to the active chain end. Understanding these different types is crucial for controlling polymer properties like molecular weight, tacticity, and branching.