polymeerointireaktion

Polymeerointireaktio, often translated as polymerization reaction, is a fundamental chemical process where small molecules, called monomers, chemically bond together to form a much larger molecule, a polymer. This process involves the sequential addition of monomer units to a growing chain. The resulting polymer consists of repeating structural units derived from the monomers. Polymerization reactions can occur through various mechanisms, broadly classified into two main types: chain-growth polymerization and step-growth polymerization.

Chain-growth polymerization, such as free-radical polymerization, involves the formation of active species (like free radicals, cations, or anions) that initiate the reaction. These active species then rapidly add monomers to the growing chain, propagating the reaction until termination occurs. Examples include the polymerization of ethylene to polyethylene or vinyl chloride to polyvinyl chloride (PVC).

Step-growth polymerization, also known as condensation polymerization, involves the reaction between functional groups on monomers or oligomers. Typically, a small molecule, such as water or methanol, is eliminated as a byproduct during each step of the chain growth. The reaction proceeds by the gradual increase in the molecular weight of the polymer, with monomers, dimers, trimers, and longer chains reacting with each other. Examples include the formation of polyesters from diols and diacids, or polyamides (nylons) from diamines and diacids. The specific conditions, catalysts, and monomers used determine the type of polymerization and the properties of the resulting polymer.