Sodium polyacrylate and water. Footage of water being poured into a beaker containing sodium polyacrylate, which absorbs the water and sets hard, as demonstrated by the beaker being turned upside down. Sodium polyacrylate is a sodium salt of polyacrylic acid, a polymer of acrylic acid (CH2CHCO2H). The structure of this polymer means it can absorb 200 to 300 times its own weight in water. It is used as a thickening and sequestering agent in detergents, nappies and other liquid-absorbing devices.