Super Siphon Polymer

Science Concept: Polymers and Viscosity. A polymer gel will climb up the side of the beaker against the force of gravity.

Materials:

Anhydrous alcohol (methyl or ethyl alcohol), 25 mL

Polyethylene oxide, 3-4 g

Fluorescent dye such as Fluorescein or rhodamine B (optional)

Food Dye (optional)

Graduated cylinder, 25 mL

2 Beakers, 600 mL

Stirring Rod

Directions:

  1. Mix 20-25 mL of alcohol with 3-4 grams of polyethylene oxide in a clean, dry 600 ml beaker. Swirl the mixture to completely wet the resin with alcohol. The polymer will not dissolve, but will be a free floating slurry.
  2. Add 350-400 mL of tap water into the alcohol-polymer mixture "in one pour". Stir the mixture very quickly until the the solution is homogeneous and thick.
  3. Pour the gel into the second 600 mL beaker and then pour it back and fourth between the two beakers to finish mixing the gel.
  4. The polyethylene oxide can be made to siphon "uphill" out of the beaker and against gravity. To start the process, raise the beaker with the gel above the empty beaker. Once the gel starts to pour, turn the raised beaker upright again. The gel will move up the side of the raised beaker as a thin film and then form thick strands as it falls. This siphoning process can be repeated indefinitely by switching the raised and lowered beakers.

Explanation:

  1. This process is called siphoning, which means that a fluid can be poured into another container without pouring the fluid. A siphon effect appears to work against the force of gravity.
  2. Polyethylene oxide is a water soluble, non ionic, high molecular weight polymer. It is a polyether in that it has an oxygen atom as every third atom, the first two atoms being carbon. The large number of oxygen atoms, each with two lone pairs of electrons, leads to extensive hydrogen bonding in a water solution. It is able to "thicken" water
  3. The long strands of the gel are formed when the large polymer molecules intertwine much like spaghetti and are cross-linked by water molecules attached to the oxygen on the adjacent polymer molecules. The result is a "viscoelastic" gel. like molasses, the gel has a high viscosity due to the large number of hydrogen bonds between the polymer molecules and that water, and is elastic since these very long molecules can both straighten, when stretched, and slide pass each other, forming fresh hydrogen bonds as they move.
  4. Polyethylene oxide is used to both thicken and a soft silky feel to many shampoos, hair conditioners, cold creams, lotions, latex paint, and detergents.

Safety: Polyethylene Oxide has a very low toxicity. It does not cause eye or skin irritation.

Disposal: The gel can be disposed in the waste can and the beakers rinsed with plenty of tap water.

Reference: Flinn Scientific, Chem Fax, Super Duper Polymer, Pub. no. 4556.