Polymer
The word polymer is derived from the Greek poly means "many" and mers means "parts". And refers to the number of repeating units held together by covalent bonds.
Polymer refers to a molecule whose structure is composed of multiple repeating chemical units, from which originate a characteristics of high molecular weight and attendant properties. Example: poly-ethylene, poly-vinyl-chloride, poly-iso-butylene, polystyrene.
Monomer:
The repeating chemical unit is called monomer. So, the starting material from which the molecules is formed is known as the monomer.
Repeating unit:
The repeating unit in the polymer is usually equivalent or nearly equivalent to the monomer. Thus the repeating unit of poly-vinyl-chloride is -CH2CHCl-, its a monomer of vinyl-chloride CH2=CHCl.
Oligomer:
When the number of repeating unit is between 2-10 in a polymer then that polymer is called Oligomer.
High Polymer:
A high polymer may be defined as one in which the number of repeating units is more than 100.
Low Polymer:
A low polymer may be defined as one in which the number of repeating units is less than 100 or equal to 100.
