As a small lab, we looked at sodium polyacrylate. Sodium Polyacrylate is a substance used in diapers, as it can soak up 300 to 800 times its volume of water, or other liquids. This occurs because of the structure of the chemical. All polymers are molecules that are made of small, repeating units that form long chains. In its dry crystal form, sodium polyacrylate is coiled. When water is added, the long chains of sodium polyacrylate stretch out. This happens because each repeating unit in sodium polyacrylate contains an area that can support a negative charge. When water is added to the polymer, these areas form negatively charged ions that repel one another and cause the polymer to stretch out. As the polymer stretches, more water molecules can associate with its areas of negative charge.
We started with a measured amount of sodium polyacrylate, taken from diapers, in a glass jar. Then Braden stirred in water gradually, causing the chemical to swell. By the end, the jar was almost completely filled! Braden said it was possible to cause the jar to overflow, but it would be a mess to clean up. The gel that it created was almost like a warm snow. However, it felt dry.
We started with a measured amount of sodium polyacrylate, taken from diapers, in a glass jar. Then Braden stirred in water gradually, causing the chemical to swell. By the end, the jar was almost completely filled! Braden said it was possible to cause the jar to overflow, but it would be a mess to clean up. The gel that it created was almost like a warm snow. However, it felt dry.