polymerisaatioon

Polymerisaatioon is the Finnish term commonly used to describe polymerization, the chemical process in which small molecules called monomers are linked into large, repeating chains called polymers. The process is foundational to plastics, synthetic fibers, and many biomaterials.

There are two broad categories: addition (chain-growth) polymerization and condensation (step-growth) polymerization.

In addition polymerization, unsaturated monomers react through reactive intermediates such as free radicals, cations, or anions, often initiated by heat, light, or chemical initiators. Coordination polymerization uses metal catalysts to control the arrangement of monomer units, improving stereoregularity, as in some polyethylene and polypropylene processes.

In condensation polymerization, monomers with two or more reactive groups join while releasing a small molecule such as water or methanol. This category includes polyesters, polyamides, and polyurethanes, among others.

Control over molecular weight and architecture is central to polymer science. Living or controlled polymerization techniques, such as ATRP or RAFT, provide precise end groups and narrow molecular weight distributions.

Representative polymers include polyethylene, polypropylene, polystyrene, poly(vinyl chloride), PET, nylons, and polyurethanes. Properties depend on chain length, branching, tacticity, and end-group functionality, determining uses in packaging, textiles, electronics, and biomedicine.

Historically, early 20th century work by Wallace Carothers and others spurred modern polymer chemistry, culminating in nylon and later diverse plastics.