Macromolecule

Macromolecule is a very large molecule formed by linking smaller units called monomers. Most macromolecules arise by polymerization, in which monomers are covalently bonded into long chains or networks. Their properties depend on composition, sequence, and architecture, including whether they are linear or branched and whether they are crosslinked or crystalline.

In biology, the principal macromolecules are proteins, nucleic acids, and polysaccharides. Proteins are polymers of amino acids linked by peptide bonds and perform a wide range of functions. Nucleic acids are polymers of nucleotides that store and transmit genetic information (DNA) or assist in gene expression (RNA). Polysaccharides are polymers of monosaccharides that serve for energy storage (starch, glycogen) and structural roles (cellulose, chitin). Lipids are large biomolecules that may form macromolecular assemblies but are not polymers of repeating monomers in the same sense.

Synthetically, macromolecules include polymers such as polyethylene, polystyrene, polyvinyl chloride, polyesters, silicones, and nylons. They are prepared by addition polymerization or condensation polymerization. Polymer architecture includes homopolymers, copolymers, block copolymers, and crosslinked networks (thermosets).

Applications span packaging, textiles, electronics, medicine, and materials science. Molecular weight, tacticity, crystallinity, and chain dynamics influence properties such as strength, toughness, elasticity, and thermal stability. The study of macromolecules combines chemistry, biology, and materials science and underpins numerous modern technologies.