This practical involves students making a slimy material from borax and PVA glue. The resultant slime is a polymer.
To make the best slime, you will need to prepare the two solutions that the students will mix, before the lesson. The first is the PVA solution. This solution needs to be 4% polyvinyl alcohol, that is, 40 g of PVA per litre of deionised water. The PVA needs to be slowly added to the deionised water and stirred using a magnetic stirrer for about 30 mins while heating at around 70 degrees until clear. Leave to cool at room temperature and store in a sealed container.
The second solution contains the borax (sodium tetraborate). Again the mixture needs to be 4% borax, 40g per litre of deionised water. Slowly add the borax to the water stirring continuously until clear. This should take around ten minutes.
The students simply need to mix the two solutions 50/50 in order to make their slime. A small amount of food colouring will make the polymer more slime like. Once made, the slime must be kept in an airtight container as it will dry out if left exposed to the air for too long.
A more simple slime can be made by the students simply by mixing 1 tbsp borax with a cup of water until clear. This is then added to a mixture comprising ¼ cup of PVA with ¼ cup of water. This can then be mixed in a bag with a sealed top until consistent.
The borax enables the glue (polyvinyl acetate) molecules to join together to form larger molecules called polymers. This makes a thickened, slimy gel.