Superabsorbent Polymers (SAP)

Superabsorbent polymers (known as SAP) are water-insoluble polymer, cross-linked copolymer of acrylic acid. It is in the form of white, odourless granules. This water-absorbing polymer is produced by acrylic acid and a cross-liner solution through polymerization. This product has the character of superabsorbent which makes this material could absorb and retain water of hundreds of times of its weight shortly. Moreover, this product is able to hold absorbed water even against pressure.

Conduct this activity as part of your comparison of physical and chemical changes. The experiment also highlights the effect of chemical structure on physical properties. In a remarkable physical change, each of 2 polymers absorbs several hundred times its own weight in water. When treated with sodium chloride, the hydrated polymer then loses water by diffusion. Although each polymer absorbs a huge amount of water, one absorbs much faster than the other. The dramatic difference in their rate of absorption is due to a small difference in their chemical structure.