• 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

  • 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

  • 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

  • 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

  • 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.