My second favourite molecule, page-3

Hyaluronic acid is one of a class of polymers that decades ago came to be known as superabsorbers. These can typically absorb around 100x their weight in water. You know those “water saving crystals” that you can buy for pot plants that swell up with water? A synthetic polyacrylate superabsorber. These are cross linked so they retain their form as a solid gel. Hyaluronic acid isn’t cross linked so it’s a viscous liquid when it absorbs water. But it does retain a huge amount of water and is important managing water distribution in tissue, maintaining hydration, providing a cosmetic plumping effect to skin, and of course providing lubrication in the synovium.