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Moon Blob: A Self-Siphoning Gel Everyone knows that water can't flow uphill. Not so fast...
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Moon Blob: A Self-Siphoning Gel

Everyone knows that water can't flow uphill. Not so fast... When a small amount of Polyox (polyethylene oxide) is mixed with water, it dissolves forming a thick, slippery, gooey, mucous-like gel. Oh, the visual imagery! When the gel is poured back and forth between two beakers, the gel mysteriously siphons from the higher held beaker to the lower one. Maybe water can flow uphill. You have to play with the stuff to believe it.

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Materials

  • Polyox (polyethylene oxide with a molecular weight of at least 4,000,000)
  • Rubbing alcohol (90% isopropyl alcohol)
  • Food coloring
  • Two beakers or clear cups
  • Water
  • Lots of paper towel

 

 

Use the following mixing instructions if you are using Polyox.

  1. Place approximately 4 grams of the Polyox powder into the bottom of the beaker.
  2. Add about 10 ml of 90% rubbing alcohol (or any other extremely dry solvent) to the Polyox. Swirl the cup to wet all of the polymer with alcohol.
  3. Fill the second beaker with approximately 400 mL of water. Add a few drops of food coloring for effect.
  4. Pour all the water mixture into the beaker with the Polyox in one controlled, swift motion. If you pour too slowly, the polymer and the water will gel-block (clump up), and if you pour too quickly, the mixture is likely to spill everywhere. Remember, this is the part that takes a little practice.
  5. Mix the water and Polyox together by pouring the liquid from beaker to beaker until the liquid begins to thicken. Don't attempt the self-siphoning activity just yet. Continue to pour the liquid from beaker to beaker to mix it thoroughly. After just a few minutes of mixing, you'll notice that the mucous-like gel flows very quickly from beaker to beaker. Hold the empty beaker below the full one and start to pour a little of the liquid into the lower beaker. What happens? The liquid will siphon itself from the top beaker to the bottom beaker. Notice how the liquid appears to defy gravity as it crawls up and over the sides of the full beaker in a "self-siphoning" kind of action.

WARNING: Don't be surprised if you become so transfixed on the self-siphoning action of the polymer that you forget to line up the bottom beaker with the top beaker. In other words, you're bound to miss the bottom beaker and your hands will be covered with goo. You'll feel like the stand-in creature in the Alien movies. Don't worry it easily washes right off your skin, but clothes, fabric and carpet is a little trickier.

How does it work?

Polyethylene oxide is a non-toxic, long chain, water soluble polymer. What makes this water based polymer so special is its high molecular weight of approximately 4,000,000. The molecular structure of Polyox promotes extensive hydrogen bonding, which allows it to be soluble in water despite the high molecular weight. It's been said that the length of the polymer chains in a single drop of the gel is some 1,700,000 miles long (give or take a few). Over the years, Polyox gained popularity by fire fighters who added very small amounts of the polymer to the water supply in pumper trucks. In theory the addition of the Polyox reduced the friction caused by the water molecules rubbing against the inside wall of the hose. The reduction of friction made the water flow more quickly through the hose. True? You be the judge.

In order to illustrate the molecular structure of Polyox, it might be helpful to picture a bowl of spaghetti all tangled up. The spaghetti-like structure causes the polymer to thicken water and provides a strong elastic effect. Although extremely elastic, the Polyox remains fluid like pancake syrup. The straight chain format of the Polyox molecule with no side chains to attach to other molecule strands allows the separate chains to slide past each other and stay fluid.

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