Polymers

Definition, Classification, &  Differences

Presented by chemistnotes.com

The word ‘polymer‘ is composed of two greek words; poly = many, and mer = simple unit.

Polymers are long-chain high molecular weight compounds obtained by the combination of a large number of simple molecules.

The simple molecules taking part in the formation of polymers are called monomers and this process of polymer formation is called polymerization.  Thus, polymerization is the process of the formation of a large molecule (polymer) by the combination of a large number of smaller molecules (monomer).

Arrow

The monomers are the repeating units of polymers.

The polymers possess distinctive physio-chemical characteristics and unique physical, mechanical and electrical properties.  These are utilized extensively in our daily life, particularly in the area of engineering and technology.

Classification of polymers

Classification of polymer based on composition

1. Homopolymer: The polymers which contain the atom of only one element in their backbone are called homopolymers. It is formed by the addition of identical repeating units.                 -A-A-A-A-A-

2. Heteropolymers: Heteropolymers contain the atoms of different elements in their backbone.

Copolymers:  The polymers which contain more than one type of monomers in their molecules are called copolymers. 

Swipe

Copolymer is categorized into the following four types:

1. Alternating copolymer         -A-B-A-B-A-B-A-B- 2. Random copolymer   -A-A-B-A-B-B-A-B-A-A-A 3. Block copolymer -A-A-A-B-B-B-B-A-A-A-A-B-B- 4. Graft copolymer consists entirely of one repeat unit and the branch chain consists of different types of repeat units.

Classification of polymer based on the type of reaction

Addition polymers: When a large number of monomers are combined together to form a large-weight polymer compound without the elimination of any small molecules like H2O, NH3, HCl, etc., the polymers formed are called addition or chain polymers.

Arrow

Condensation polymers: The polymers formed by the condensation between monomers along with the elimination of smaller molecules are called condensation or step-growth polymers.

Swipe

Classification of polymer based on the action of heat

Thermoplastics:  The plastics or polymers which become soft on heating and can be molded and remolded into different desired shapes are called thermoplastics.  It is formed by addition polymerization.

Thermosetting plastics: The polymers which do not soft on heating and thus cannot be molded and remolded into different shapes are called thermosetting plastics. It is formed by condensation polymerization and possesses strong intermolecular forces with extensive cross-links between molecular chains.

Swipe

For Detail Information Please Visit

Website

Thank You

Chemistnotes