radikaalipolymeroitumisen

Radical polymerization, or radikaalipolymerointi in Finnish, is a chain-growth polymerization mechanism in which reactive radical species are involved in the growth of polymer chains. This approach is widely used to polymerize vinyl monomers such as styrene, acrylonitrile, and acrylates, among others. Initiation involves generation of radical centers, often through thermal decomposition of initiators like azobisisobutyronitrile (AIBN) or benzoyl peroxide, or via photoinitiators under light exposure. Propagation adds monomer units to growing chains, while termination occurs by radical-radical combination or disproportionation. The process is highly sensitive to oxygen, which scavenges radicals and inhibits polymerization, hence reactions are often carried under inert atmosphere or with oxygen-removing additives.

Controlled variants include living radical polymerization techniques such as RAFT (reversible addition-fragmentation chain-transfer) and ATRP (atom transfer radical polymerization), which employ specialized mediators to regulate growth and broaden molecular weight control and architecture. These methods reduce chain-transfer events and provide narrow molecular weight distributions and potential for block copolymers.

Applications include production of plastics, elastomers, coatings, adhesives, and hydrogels. Typical advantages: rapid polymerization, broad monomer scope, simple equipment. Limitations: control over molecular weight distribution, residual initiator and oxygen sensitivity, potential for radical-induced side reactions, and thermal or photostability concerns.