Polymer

A polymer () (poly-, “many” + -mer, “parts”) is a large molecule, or macromolecule, composed of many repeated subunits. Because of their broad range of properties, both synthetic and natural polymers play an essential and ubiquitous role in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass relative to small molecule compounds produces unique physical properties, including toughness, viscoelasticity, and a tendency to form glasses and semicrystalline structures rather than crystals. The term “polymer” derives from the ancient Greek word (polus, meaning “many, much”) and (meros, meaning “parts”), and refers to a molecule whose structure is composed of multiple repeating units, from which originates a characteristic of high relative molecular mass and attendant properties. The units composing polymers derive, actually or conceptually, from molecules of low relative molecular mass. The term was coined in 1833 by J ns Jacob Berzelius, though with a definition distinct from the modern IUPAC definition.If two substances had empirical formulae that were integer multiples of each other — e.g., acetylene (C2H2) and benzene (C6H6) — Berzelius called them “polymeric”. See: J ns Jakob Berzelius (1833) “Isomerie, Unterscheidung von damit analogen Verh ltnissen” (Isomeric, distinction from relations analogous to it), Jahres-Bericht ber die Fortschitte der physischen Wissenschaften ‘, 12 : 63-67. From page 64: “Um diese Art von Gleichheit in der Zusammensetzung, bei Ungleichheit in den Eigenschaften, bezeichnen zu k nnen, m chte ich f r diese K rper die Benennung polymerische (von mehrere) vorschlagen.” (In order to be able to denote this type of similarity in composition [which is accompanied] by differences in properties, I would like to propose the designation “polymeric” (from , several) for these substances.)Originally published in 1832 in Swedish as: J ns Jacob Berzelius (1832) “Isomeri, dess distinktion fr n dermed analoga f rh llanden,” rsber ttelse om Framstegen i Fysik och Kemi, pages 65-70 ; the word “polymeriska” appears on page 66. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, who spent the next decade finding experimental evidence for this hypothesis. Polymers are studied in the fields of biophysics and macromolecular science, and polymer science (which includes polymer chemistry and polymer physics). Historically, products arising from the linkage of repeating units by covalent chemical bonds have been the primary focus of polymer science; emerging important areas of the science now focus on non-covalent links. Polyisoprene of latex rubber and the polystyrene of styrofoam are examples of polymeric natural/biological and synthetic polymers, respectively. In biological contexts, essentially all biological macromolecules’i.e., proteins (polyamides), nucleic acids (polynucleotides), and polysaccharides’are purely polymeric, or are composed in large part of polymeric components’e.g., isoprenylated/lipid-modified glycoproteins, where small lipidic molecule and oligosaccharide modifications occur on the polyamide backbone of the protein. The simplest theoretical models for polymers are ideal chains.