Polymer Crosslinking Lab
Purpose: To observe the effect of polymer crosslinking.
Materials: glue and water solution, 4% borax solution, paper cup, wooden stick, food coloring, plastic baggy
1. Obtain approximately 65 ml of glue and water solution
2. Make a 20 g solution of water and sodium tetraborate that is 4% sodium tetraborate.
3. Using 20 ml aliquots of glue and water solution and 3 different amounts of borate solution, determine a ratio of Borate to glue and water solution which maximizes the “bounciness” or “sliminess” of the glue and water molecules. Make a data table!!!! (Include: amounts and obervations)
** DO NOT USE A GRADUATED CYLINDER TO MEASURE THE GLUE AND WATER SOLN. (suggestion: good mixtures include glue and water solutions with a 5 – 20% borax solution component.
4. Pour the solution from the cup into a baggy after mixing. Knead the baggy and observe what happens. You may put food coloring in the bag if you wish.
Conclusions
1. Draw the vinyl alcohol monomer. (aka: ethenol)
2. Draw a polymer consisting of 10 vinyl alcohol monomers.
3. Draw a second vinyl alcohol polymer and show how the following molecule (borate) links the two polymers together. The oxygen’s in the borate ion are weakly attracted to the hydrogen’s in the alcohols in the polymer chains.
4. How did increasing the amount of borate affect the viscosity of the polymer? How can you make it the slimiest? How can you make it the bounciest?
5. What do you think would happen if you were to heat up your slime? What if you cooled it?
6. What must be happening at the molecular level to allow the slime to bend and stretch without falling apart? *Think Intermolecular Forces.
7. Draw a vinyl chloride monomer (aka: chloroethene)
8. Draw a polymer consisting of 10 vinyl chloride monomers.
9. Would it be more appropriate to call this type of polymer formation an addition, or a condensation (dehydration) reaction?
10. Draw 2 amino ethanoic acid.
11. Draw 10, 2-amino ethanoic acid molecules that are connected into one chain. The –OH from the carboxyl group will combine (and leave) with the –H from the amine group.
12. Would it be more appropriate to call this reaction an addition or a condensation (dehydration) reaction?
Conclusions
1. Draw the vinyl alcohol monomer. (aka: ethenol)
2. Draw a polymer consisting of 10 vinyl alcohol monomers.
3. Draw a second vinyl alcohol polymer and show how the following molecule (borate) links the two polymers together. The oxygen’s in the borate ion are weakly attracted to the hydrogen’s in the alcohols in the polymer chains.
4. How did increasing the amount of borate affect the viscosity of the polymer? How can you make it the slimiest? How can you make it the bounciest?
5. What do you think would happen if you were to heat up your slime? What if you cooled it?
6. What must be happening at the molecular level to allow the slime to bend and stretch without falling apart? *Think Intermolecular Forces.
7. Draw a vinyl chloride monomer (aka: chloroethene)
8. Draw a polymer consisting of 10 vinyl chloride monomers.
9. Would it be more appropriate to call this type of polymer formation an addition, or a condensation (dehydration) reaction?
10. Draw 2 amino ethanoic acid.
11. Draw 10, 2-amino ethanoic acid molecules that are connected into one chain. The –OH from the carboxyl group will combine (and leave) with the –H from the amine group.
12. Would it be more appropriate to call this reaction an addition or a condensation (dehydration) reaction?
Oobleck / Goop1. Can you roll your slime into a ball? If you can, does it bounce? What happens if you set the ball on the table?
2. Can you roll your slime into a "snake." If you can, pull on the snake gently. Does it stretch or break?
3. Do you think the slime is a solid or a liquid? Explain.
4. Try to use a coin to make an imprint in the slime. Does the imprint last? / 1. Can you roll your slime into a ball? If you can, does it bounce? What happens if you set the ball on the table?
2. Can you roll your slime into a "snake." If you can, pull on the snake gently. Does it stretch or break?
3. Do you think the slime is a solid or a liquid? Explain.
4. Try to use a coin to make an imprint in the slime. Does the imprint last?
Post-lab questions:
1. How is the cornstarch slime different than the glue slime?
2. Which one is "stronger"? Explain.
3. Based on your observations, which slime exhibited cross-linking? Explain.
4. What do you think the cross-linking agent was in your slime? Explain.