Matt Treadwell

Polyurethane Foam

Science Concept:

Two monomers react producing a three-dimensional polymer by cross-linking many rows of linear polymers.

Materials:

Obtain a kit from Flinn Scientific with solutions A and B.

Solution A (trichloroflouromethane and polymer alcohol)

Solution B (poly functional isocyanate)

styrofoam cup

wooden stick for stirring

Directions:

* Place a mark on the cup about 1/3 of the way up from the bottom. Place a second mark of equal distance up from the first.

* Pour solution A up to the first mark and pour B up to the second mark on the styrofoam cup.

* Begin stirring the thick solution with wooden stirring stick for about 30 seconds .

* The reaction might take 1-2 minutes, so be patient.

Introduction:

I felt like making a present for my teacher, so I felt this would be the best gift to give to him.

Explanation:

A polymer is a long chain of molecule made of many repeating monomer units. In this experiment, the monomers units we call molecule A and molecule B. A adds to B and A adds to B many, many times to form the polymer. A-B-A-B-A-B-A-B are linear chains formed by monomers.

In addition these molecules have a third place for the reaction to take place. The individual polymer chains are cross linked together. The cross-linking of the two monomers A and B is what caused the reaction. Many alternating units of A-B-A-B are cross-linked. The main cause of it to be rigid and foam out is the cross-links along with the formation of bubbles. Carbon dioxide bubbles are released which also contributes to the production of the foam. The three dimensional polymer is called polyurethane foam. The reaction gives off heat. If you were to place your hand above the reaction, you can feel the heat rising. In a few minutes, the reaction is complete and we will be able to touch it.

Reference: Shakhashari, B, Chemical Demonstrations, Vol. 1, U. Wisconsin Press, 1983, p. 216.