Polymeri

Polymeri, a term used in several languages to denote large molecules built from repeating subunits called monomers, are the fundamental building blocks of many materials and biological systems. They form by polymerization, a process that links monomers into long chains or networks. Polymerization methods are commonly categorized as addition (chain-growth) polymerization or condensation (step-growth) polymerization. In addition polymerization, active centers add monomer units one by one, often with little byproduct. Condensation polymerization produces polymers along with small molecules such as water or methanol.

Polymers occur naturally as well as synthetically. Natural polymers include DNA, proteins, cellulose, starch, and natural rubber. Synthetic polymers include polyethylene, polystyrene, polypropylene, and polyvinyl chloride. The properties of a polymer depend on molecular weight, molecular-weight distribution, branching, tacticity (the arrangement of stereocenters), and crystallinity. These factors influence strength, toughness, flexibility, transparency, thermal stability, and processability. Polymers are broadly classified as thermoplastics (which soften when heated and can be reshaped), thermosets (which cure into a rigid network), and elastomers (which are highly elastic).

Applications span a wide range of sectors, including packaging, construction, textiles, automotive, electronics, and medicine. Environmental considerations are increasingly important, covering resource use, recyclability, and end-of-life management. Advances in polymer science seek to tailor monomer selection and polymer architecture, employ copolymerization, and develop processing methods to achieve desired performance while reducing environmental impact.