Polymeren

Polymers, also known as polymeren in Dutch, are large molecules composed of repeating subunits called monomers, typically linked by covalent bonds to form long chains. The term also describes the class of materials built from these macromolecules, which can occur naturally or be synthesized. Natural polymers include cellulose, starch, proteins, and nucleic acids, which perform essential biological and structural roles. Synthetic polymers include plastics, fibers, and elastomers such as polyethylene, polystyrene, polyvinyl chloride, nylon, and silicone-based polymers.

Polymerization is the chemical process by which monomers join to form polymers. Chain-growth (addition) polymerization involves successive addition of monomer units to a growing radical or ion, while step-growth (condensation) polymerization builds the chain through alternating monomer units and by releasing a small molecule such as water. The properties of a polymer depend on the monomer identity, the length and distribution of chains, the degree of branching, and the crystallinity. Important properties include molecular weight, glass transition temperature (Tg), melting temperature (Tm), elasticity, toughness, and chemical resistance.

Polymers are commonly classified as thermoplastics, thermosets, or elastomers. Thermoplastics can be melted and reshaped; thermosets form cross-linked networks that do not remelt after curing; elastomers are stretchable polymers with reversible deformation. Applications span packaging, construction, textiles, automotive, electronics, medicine, and consumer goods. Processing methods include extrusion and injection molding for thermoplastics, and curing for thermosets.

Environmental considerations include energy use, recyclability, and end-of-life management. Some polymers are designed to be biodegradable or compostable, while others persist in the environment. Advances focus on sustainable feedstocks, recycling technologies, and reducing microplastic pollution.