What is a polymer?
A polymer is a very large molecule made by joining many small units, called monomers, into a long chain. The process of joining monomers together is called polymerisation. A single polymer molecule may contain thousands of repeating units, which is why polymers are sometimes called macromolecules.
Key idea
Many monomers (small units) join by polymerisation to form one long polymer chain. For example, many ethene molecules join to form polythene.
Natural and synthetic polymers
Polymers can be natural or synthetic (man-made).
- Natural polymers: natural rubber (from the latex of rubber trees), cellulose and starch (in plants), and proteins.
- Synthetic polymers: polythene (plastic bags), PVC (pipes), polystyrene (foam cups) and nylon (fabric).
Malaysia has long been a major producer of natural rubber, tapped from rubber trees as latex and then processed into products such as gloves and tyres.
Properties and uses
Most synthetic polymers are light, strong, flexible, waterproof and unreactive, and they are good insulators of heat and electricity. These properties make them useful for packaging, clothing, pipes and electrical casings.
Example
The plastic casing around an electrical plug is made of a polymer because it does not conduct electricity and does not corrode, keeping the user safe.
The environmental problem
Many synthetic polymers are non-biodegradable – microorganisms cannot break them down, so they remain in the environment for a very long time and cause pollution. Burning them can release harmful gases. This is why we are encouraged to reduce, reuse and recycle plastics. Scientists are now developing biodegradable polymers that microorganisms can break down more easily, helping to cut down the growing problem of plastic waste in our rivers and oceans.
Remember
Monomer = the small unit; polymer = the long chain of many monomers. Natural rubber is a polymer, but metals like copper and simple molecules like water are not.