Science: An Elementary Teacher’s Guide/Organic Molecules
What is a Polymer?[edit | edit source]
A polymer (meaning "many parts") is a large molecule (a macromolecule), composed of many repeated subunits called monomers ("single parts"). Due to their broad range of properties, both synthetic and natural polymers play essential roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene and nylon 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, a chemical reaction where the monomers are joined to each other. Their consequently large molecular mass relative to small molecule compounds produces unique physical properties, including toughness, elasticity, and a tendency to form glasses and semicrystalline structures rather than crystals.
Inorganic vs Organic[edit | edit source]
Polymers are of two types: naturally occurring and synthetic or man made.
Natural polymeric materials such as shellac, amber, wool, silk and natural rubber have been used for centuries. A variety of other natural polymers exist, such as cellulose, which is the main constituent of wood and paper.
The list of synthetic polymers, roughly in order of worldwide demand, includes polyethylene, polypropylene, polystyrene, polyvinyl chloride, synthetic rubber, phenol formaldehyde resin (or Bakelite), neoprene, nylon, polyacrylonitrile, PVB, silicone, and many more. More than 330 million tons of these polymers are made every year.
Most commonly, the continuously linked backbone of a polymer used for the preparation of plastics consists mainly of carbon atoms. A simple example is polyethylene, whose repeating unit is based on the ethylene monomer. However, other structures do exist; for example, elements such as silicon form familiar materials such as silicones, examples being Silly Putty and waterproof plumbing sealant. Oxygen is also commonly present in polymer backbones, such as those of polyethylene glycol, polysaccharides (in glycosidic bonds), and DNA (in phosphodiester bonds).