Polymer

Name:
Polymer
Detailed information:
A macromolecule formed by the chemical union of five or more identical combining units called monomers. In most cases the number of monomers is quite large (3500 for pure cellulose) and often is not precisely known. In synthetic polymers this number can be controlled to a predetermined extent, e.g., by short-stopping agents. (Combinations of two, three, or four monomers are called, respectively, dimers, trimers, and tetramers and are known collectively as oligomers.) A partial list of polymers by type is as follows:

Inorganic: siloxane, sulfur chains, black phosphorus, boron-nitrogen, siliconesOrganic

1. Natural
   1. Polysaccharides: starch, cellulose, pectin, seaweed gums (agar, etc.), vegetable gums (arabic, etc.).
   2. Polypeptides (proteins): casein, albumin, globulin, keratin, insulin, DNA
   3. Hydrocarbons: rubber and gutta-percha (polyisoprene)
2. Synthetic
   1. Thermoplastic: elastomers (unvulcanized), nylon, polyvinyl chloride, polyethylene (linear), polystyrene, polypropylene, fluorocarbon resins, polyurethane, acrylate resins
   2. Thermosetting: elastomers (vulcanized), polyethylene (cross-linked), phenolics, alkyds, polyesters
3. Semisynthetic: cellulosics (rayon, methylcellulose, cellulose acetate), modified starches (starch acetate, etc.)