macromolecular

Macromolecular is an adjective referring to macromolecules, large molecules with high molecular weight. In chemistry and materials science, macromolecules are typically polymers—chains of repeating units called monomers linked by covalent bonds. The degree of polymerization, the number of repeating units, governs many properties. Molecular weight is described by measures such as number-average Mn and weight-average Mw; the polydispersity index PDI = Mw/Mn indicates the breadth of the molecular weight distribution.

Macromolecules occur in natural and synthetic forms. Natural macromolecules include proteins (made from amino acids), nucleic acids (made from nucleotides), and polysaccharides like cellulose and starch. Synthetic macromolecules include plastics (polyethylene, polystyrene), engineering polymers (polycarbonate, polyimide), and elastomers (polyisoprene). They can be linear, branched, or crosslinked, and this architecture influences melting or glass transition temperatures, mechanical strength, solubility, and other properties.

Polymerization methods include addition (chain-growth) polymerization and condensation (step-growth) polymerization. The resulting structure and functional groups determine reactivity and applications. Macromolecules are studied with techniques such as gel permeation chromatography for molecular weight distribution, light scattering for size, spectroscopy for structure, and calorimetry for thermal properties.

Applications span materials science, biology, medicine, and nanotechnology. Natural macromolecules perform essential biological roles, while synthetic macromolecules underpin modern plastics, coatings, adhesives, and biodegradable materials. The term macromolecular highlights the size and predominantly polymeric nature of these substances, which yield properties not found in small molecules.