SCH4C        Lab #7 - Hydrogen Bonding in Slime

Introduction:  Two clear liquids are mxed.  The result is a shimmery fluid polymer that can be shaped, that flows and that will sheer if twisted quickly.

Solutions:
1.      Polyvinyl alcohol is a 4% solution: Add 4 grams to 100 mL of water.    Heat to 70oC until the solution clears.  Do not boil.

2.    Sodium tetraborate is a 4% solution: Add 4 grams of sodium borate, Na2B4O7.10H2O, to 100 mL of water.

Procedure:
1.    Measure 50 mL of polyvinyl alcohol soltuion into a small beaker and observe its properties.

2.    Measure 7-8 mL of sodium tetraborate solution into another small beaker and observe its properties.

3.    Choose a food colouring and add 1 drop of the food colouring to the sodium tetraborate solution.

4.    Pour sodium tetraborate slowly into the polyvinyl alcohol solution while stirring vigorously with a wooden stick.

5.    Examine the properties of the cross-linked polymer.

6.    Experiment to see how far the polymer will flow from your hand.

Reactions:
1.    Polyvinyl alcohol is a polymer derived from the monomer vinyl alcohol.

2.    The borate forms a complex structure called tetraborate, B4O5(OH)42-, that links the poly vinyl alcohol polymer strands together with hydrogen bonds.

Questions:
1.    Describe the physical characterisitcs of the polyvinyl alcohol solution.
2.    Describe the physical characteristics of the sodium tetraborate solution.
3.    The manufactured polymer has some unique characteristics. Describe them.
4.    How did the properties of the polyvinyl alcohol change after it was cross-linked.
5.    Do you think the polymer is "slimey"? Suggest a better name.
6.    What does it mean if the polymer is cold while it is flowing?