Polymers are either natural or synthetic substances that are made of very large molecules. Natural polymers are naturally occurring both in plants and animals. Cellulose, lignin, proteins, nucleic acids and starch are natural polymers which are classified as organic and they have different functions. Cellulose enables plant cells to remain strong and rigid while proteins are metabolized during starvation to provide animals with energy. Nucleic acids contain the genetic material (DNA and RNA) which is transferred from one living organism to another.
Inorganic polymers are also found in nature. Diamond and graphite are inorganic polymers of carbon. The two have different bonding making them have different chemical and physical properties. Graphite is used as a lubricant, to make pencils and as a conductor or electricity because it has a delocalized electron. On the other hand, Diamond is used to making drilling bits to help to drill other metals because its molecules are strongly bonded by covalent bonds.
Synthetic polymers produced through a number of reactions where monomers are added. Polythene is an example of a polymer that is formed when numerous ethylene monomers are reputedly added. Polythene is translucent, thermoplastic and crystalline in nature. It is used to manufacture bottles and containers, coat and package products and in the textile industry to make molded objects. Polyisoprene and polychloroprene are also additional polymers (synthetic polymers that are formed by adding monomers) that are used to manufacture synthetic rubber. On the other hand, polystyrene can be used in making toys and other plastic objects because it can be colored to any shade.
i. Polymers formed when a hydrogen atom in ethylene is replaced by a chlorine atom
Polyvinyl chloride is a hard, tough, thermoplastic and colorless polymer that can be used to manufacture fibers, foams and films.
Vinyl acetate is another example of a polymer that is used as an adhesive and coating different objects. This type of polymer can copolymerized with vinyl chloride to form thermoplastic materials which have a range of uses e.g. as plastics.
ii. Polymers with oxygen or nitrogen atoms
Polyformaldehyde is crystalline in nature, it is resistant to abrasion and solvent action and has a high melting point. As a result of these properties, this polymer is used to manufacture different parts of machines such as bearings and gears.
Polyester is used to manufacture films and fibers e.g. Dacron. This polymer can also be used to make molded objects.
Polyamides are mainly naturally occurring protein casein that’s found in milk and zein that’s found in maize. These polymers are used to make coatings, plastics, fibers and adhesives.
iii. Polymers formed from repeated urethane group
Polyurethanes is another family of polymers that are formed from a liner repetition of urethane group. They are used in making soft and rigid foams, spandex (an elastomeric fiber) and coating bases.
Silicone is polymers formed when organic and inorganic compounds are mixed. Silicones that have low molecular weight are used as oils and greases while silicones which have a higher molecular weight are used to lubricate moving parts because they are stable at very high temperatures.