Polymers

Polymers are large molecules made from many small repeating units known as monomers.
The process by which monomers combine to form polymers is called polymerisation.
The two major types of polymerisation are addition polymerisation and condensation polymerisation.
Polymers can be described as either linear, branched, or cross-linked depending on the structure of their molecules.

Addition Polymers

Addition polymers are formed through the process of addition polymerisation where all the atoms in the monomer units are included in the polymer.
This usually involves unsaturated monomers (containing double bonds). These double bonds are converted into single bonds during the process to allow the formation of a polymer chain.
Some common examples include polyethylene, polypropylene, polystyrene, and polyvinyl chloride (PVC).
Properties of these polymers include resistance to chemicals and electricity, stiffness, and low cost of production.

Condensation polymers are formed through the process of condensation polymerisation where small molecules such as water, ammonia or hydrogen chloride are eliminated during the formation of the polymer.
Monomers involved usually have two different functional groups on each end, enabling the formation of a chain.
A common example of a condensation polymer is polyesters. They are typically used in the textile industry due to their durability, easy care requirements, and resistance to wrinkles.

Natural polymers are found in nature and include proteins, nucleic acids, and polysaccharides (such as starch and cellulose).
Essentials of life such as DNA and proteins are examples of natural polymers.
They form the structural components of many natural substances such as wool, silk, rubber, and cellulose.
Cellulose, found in plant cell walls, is the most abundant natural polymer.

Synthetic polymers are man-made polymers and include plastics, synthetic fibres, and synthetic rubbers.
They are created through human industrial processes typically involving the manipulation of crude oil derivatives.
Synthetic polymers can be designed to have specific properties and uses, making them versatile for various applications.

Biodegradable polymers are designed to degrade through the action of living organisms.
They are often made from renewable resources and have increased in demand due to environmental concerns with non-biodegradable polymers.
Some examples include polylactic acid (PLA), which is made from corn starch, and polyhydroxyalkanoates (PHAs), which are made by bacteria under nutrient-limited conditions.