Lisäyspolymerisaatio

Lisäyspolymerisaatio, also known as addition polymerization, is a fundamental chemical process in polymer science. It involves the sequential addition of monomers to a growing polymer chain without the loss of any atoms. This contrasts with condensation polymerization, where small molecules like water are eliminated during the reaction.

The mechanism of addition polymerization typically involves initiation, propagation, and termination steps. The initiation step generates an active center, such as a free radical, anion, or cation, on a monomer molecule. This active center then reacts with another monomer, forming a new active center at the end of the growing chain. This propagation step repeats, adding many monomer units to the chain. The termination step ends the growth of the polymer chain, often through combination or disproportionation of active centers.

Common monomers that undergo addition polymerization include alkenes, such as ethylene, propylene, and styrene. These monomers typically contain a carbon-carbon double bond that can be opened to form the single bonds linking the monomers in the polymer backbone. Examples of polymers formed by addition polymerization include polyethylene, polypropylene, and polystyrene, which have widespread applications in packaging, textiles, and construction. The control over molecular weight and polymer architecture can be achieved through careful selection of reaction conditions and initiators.