Condensation Polymers (A-Level Chemistry)
Condensation Polymers
Condensation Polymers
Monomers
Condensation polymers are made from:
- Two different monomers – Two different monomer molecules with different functional groups, which can react with each other. Each monomer molecule contains an identical functional group at either end of the molecule.
For example, carboxylic acid groups on one molecule and alcohol groups on the other molecule, or acyl chloride and amine groups on each respective end:
HOOC-R-COOH and HO-R-OH
ClOC-R-COCl and H₂N-R-NH₂
- A single type of monomer – A single type of monomer molecule with different functional groups on each end of the molecule. The two functional groups must be able to react with each other.
For example a carboxylic acid group or acyl group on one end and an alcohol group on the other end:
HOOC-R-OH or ClOC-R-OH or ClOC-R-NH₂
Polymerisation
A small molecule is lost from every condensation polymerisation reaction.
If a carboxylic acid is involved, water is always lost.
If an acyl chloride is involved hydrogen chloride is always lost.
The type of polymer formed depends on the functional groups which react together.
Condensation Polymers: Polyesters
A polyester is the condensation polymer that forms from the reaction between:
- A dicarboxylic acid – A dicarboxylic acid (HOOC-R-COOH) has a carboxylic acid group on each end of the molecule.
- A diol – A diol (HO-R-OH) has an alcohol group on each end of the molecule.
The carboxylic acid groups react with the alcohol groups to make esters.
Water molecules are lost in the reaction.
Ester links are made which join the monomer molecules together.
The diagram below shows what happens when one molecule of dicarboxylic acid reacts with one molecule of diol.
Making Terylene – a Polyester
Terylene is made from adding benzene-1,4-dicarboxylic acid with ethane-1,2-diol.
The diagram below shows what happens when many molecules (n) of benzene-1,4-dicarboxylic acid reacts with many molecules (n) of ethane-1,2-diol.
The repeating unit for Terylene is shown.
Terylene is used to make clothing, tire cords, and sails for boats.
Intermolecular Bonds
Polyesters contain ester links. The ester link contains permanent dipole-dipole forces within the polymer chains.
The permanent dipole-dipole forces produce forces of attraction between the polymer chains, in addition to Van der Waals forces.
Condensation polymers are a type of polymer that are formed through a process known as condensation polymerization. In this process, small molecules called monomers are chemically combined to form a long chain polymer molecule.
Condensation polymers are different from addition polymers in that they are formed through a process that involves the elimination of a small molecule, such as water, during the polymerization reaction. Addition polymers, on the other hand, are formed through a process that adds monomers together without the elimination of any by-products.
Some common examples of condensation polymers include nylon, polyester, and melamine. These materials have a wide range of applications, from textiles and clothing to kitchenware and electrical components.
Condensation polymers have a number of advantages, including high strength, durability, and heat resistance. They are also versatile materials that can be molded into a variety of shapes and sizes, making them suitable for a wide range of applications.
Condensation polymers are produced on an industrial scale through a process called polymerization, which involves the reaction of monomers to form a polymer chain. This reaction is typically carried out in large reactors and can be controlled to produce polymers with specific properties.
One potential drawback of using condensation polymers is that they may be more brittle and less flexible than other types of polymers, such as addition polymers. They may also be more difficult to process and recycle than other materials, which can lead to environmental concerns. However, researchers are continually working to develop new and improved condensation polymers with improved properties.
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