polymerizes

Polymerizes is the third-person singular present tense form of the verb polymerize, meaning to convert monomer units into a polymer by forming chemical bonds. In chemistry, polymerization describes the process by which repeating structural units—monomers—link to form long chain molecules called polymers. The term can apply to synthetic processes in industry as well as to biological polymerization, such as nucleic acids and proteins, when described at a basic level.

Polymerization occurs through different mechanisms. Addition, or chain-growth polymerization, builds polymers by successive addition of activated monomer units and includes free-radical, anionic, cationic, and coordination polymerizations. Step-growth, or condensation polymerization, grows polymers by successive reactions between multifunctional monomers, often with loss of a small molecule like water or methanol. The mechanism determines molecular weight, structure, and properties of the product.

Key parameters include monomer concentration, temperature, solvent, initiator or catalyst, and time. In chain-growth polymerization, initiation, propagation, and termination steps control the polymer chain length, while chain transfer can adjust molecular weight. In condensation polymerization, reaction extent and removal of byproducts influence polymer formation. Polymerization kinetics affect rate and molecular weight distribution, which in turn influence material properties.

Common polymers formed by polymerization include polyethylene from ethylene, polystyrene from styrene, polyvinyl chloride from vinyl chloride, and polyesters such as PET. Biopolymers arise from biological polymerization, including DNA, RNA, and proteins. The study and control of polymerization have been central to materials science since the early 20th century, with notable advances in catalysts and reaction engineering enabling modern plastics and fibers.