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An essential concept which defines polymer
Polymer

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties....
 structure, the repeat unit is the simplest structural unit of a polymer chain. So a polymer consists of repeat units linked together, like the beads of a necklace. One of the simplest repeat units is that of polyethylene
Polyethylene

Polyethylene or polythene is a thermoplastic commodity heavily used in consumer products . Over 60 million tons of the material are produced worldwide every year....
:

-[CH2-CH2-]n-

while polypropylene
Polypropylene

Polypropylene or polypropene is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes....
 has the repeat unit

-[CH2-CH(CH3)]n-

The subscript "n" denotes the degree of polymerisation, that is, the number of units linked together.






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An essential concept which defines polymer
Polymer

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties....
 structure, the repeat unit is the simplest structural unit of a polymer chain. So a polymer consists of repeat units linked together, like the beads of a necklace. One of the simplest repeat units is that of polyethylene
Polyethylene

Polyethylene or polythene is a thermoplastic commodity heavily used in consumer products . Over 60 million tons of the material are produced worldwide every year....
:

-[CH2-CH2-]n-

while polypropylene
Polypropylene

Polypropylene or polypropene is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes....
 has the repeat unit

-[CH2-CH(CH3)]n-

The subscript "n" denotes the degree of polymerisation, that is, the number of units linked together. The molecular mass of the repeat unit, MR, is simply the sum of the atomic mass
Atomic mass

The atomic mass is the mass of an atom, most often expressed in Atomic mass units. The atomic mass may be considered to be the total mass of protons, neutrons and electrons in a single atom ....
es of the atom
Atom

|-! bgcolor=gray | Properties|-||}The atom is a basic unit of matter consisting of a dense, central atomic nucleus surrounded by a electron cloud of electric charge electrons....
s within the repeat unit. The molecular mass of the chain is just the product nMR. Other than monodisperse
Monodisperse

A collection of objects are called monodisperse or monosized if they have the same size, shape and mass. A sample of objects that have an inconsistent size, shape and mass distribution are called polydisperse....
 polymers, there is normally a molar mass distribution
Molar mass distribution

In linear polymers the individual polymer chains rarely have the exact same degree of polymerization and molar mass, and there is always a distribution around an average value....
 caused by chains of different length.

Vinyl Polymers


More complex repeat units occur in vinyl polymer
Vinyl polymer

Vinyl polymers are a group of polymers derived from vinyl monomers. Their backbone is an extended alkane chain, made by polymerizing an alkene group into a chain ....
s, where one of the hydrogen atom
Hydrogen atom

A hydrogen atom is an atom of the chemical element hydrogen. The Electric charge neutral atom contains a single positively-charged proton and a single negatively-charged electron bound to the nucleus by the Coulomb force....
s is substituted by another different atom, or by a larger fragment. So PVC
PVC

Polyvinyl chloride is a plastic.PVC may also refer to:*Param Vir Chakra, India's highest military honor*Peripheral venous catheter*Permanent virtual circuit, a term used in telecommunications and computer networks...
 for example possesses a chain in which the hydrogen atom is substituted by a chlorine
Chlorine

Chlorine...
 atom:

-[CH2-CHCl]n-

Polystyrene
Polystyrene

Polystyrene , sometimes abbreviated PS, is an Aromaticity polymer made from the aromatic monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry....
 has a chain where the substituent is a phenyl group
Phenyl group

In organic chemistry, the phenyl group or phenyl ring is the functional group with the formulawhere the six carbon atoms are arranged in a cyclic ring structure....
 (C6H5), corresponding to a benzene ring minus one hydrogen:

-[CH2-CH(C6H5)]n-

See also

  • Copolymers
  • Polymers