How Do Water Absorbing Polymer Beads Work?

by Wayne Jones of Aqua Gems of Idaho LLC ( 27-Aug-2009 )

Have you ever noticed what happens to a disposable baby diaper if the child wearing it wanders into a fountain or wading pool?  The diaper becomes very bloated, and if a seam rips you will notice a gel seeping from the tear.  This is an example of how water absorbing polymers work. Water’s molecule makes it sticky.  Oxygen attracts electrons, so it is mildly negative.  Hydrogen carries a slight positive charge.  This means that the water molecule has both positive and negatively charged ends, and it behaves like a magnet.  Polymers, whether natural or man-made, are long chains of molecules.  Polymers like cotton or the gel filling of a diaper offer many opportunities for water to bond with that chain of molecules. Most man-made polymers are hydrophobic, meaning that they do not absorb water.  This is a good thing because it makes things like plastic cups and bags useful.  Many natural polymers absorb water, which is why cotton towels help dry you off after a swim.  Likewise a few artificial polymers are hydrophilic, meaning that they will absorb water.  One of the most common applications of water absorbing polymers is the gel insert in disposable diapers.  Other applications include salts used in surgery to stop bleeding. Water absorbing polymers have another useful property.  In addition to absorbing water, they will also release water, but they typically do so at a measured pace.  As a result, the beads can be used to provide a steady release of water to plants, cut flowers, etc.  Landscaping and home supply stores often sell crystals for landscaping use, but you can also purchase polymers that have been shaped into a marble-like liquid bead. Another interesting property of these polymers is that they and refract light much light a glass marble or fine crystal will.  As a result, crafters and floral arrangers often use these aqua beads to enhance cut flowers, plants, candle centerpieces or other similar arrangements.  When dry, the beads are small and easily shipped.  Hydration usually takes between 4-6 hours and once hydrated the beads are significantly larger, but pliable and light.  As a result, they provide a colorful alternative to soil, water or other mediums.