Have you ever played with Silly Putty or Gak? Did
you ever wonder whether it was a liquid or a solid?
What gave Silly Putty or Gak its unique properties?
What is a cross-linked polymer? What is a dilatant?
In order to answer these questions, we have to play with polymers!
Materials:
 30 ml Poly-vinyl acetate C4H6O2 (monomer)
(Elmer’s Glue, not washable type)

2 Tbs (Heaping) Sodium tetrborate Na2B4O7 – H2O
(Borax Laundry Detergent)

45 ml H2O

30 ml plastic cup

12 oz plastic cup

Coffee filter

Stirrer (popsicle stick or spoon)

2 quart size Ziploc bags

Paper towels
Poly-vinyl Acetate
(PVA)
Procedure:
1)
2)
3)
4)
5)
6)
7)
Measure 30 ml of glue into 30 ml plastic cup
Add few drops of food coloring if desired
Transfer colored glue to 12 oz plastic cup
Add 45 ml H2O to glue (use 30 ml plastic cup and measure 1 ½ cups)
Thoroughly stir glue & water mixture
Pour glue water mixture into one Ziploc bag
Add Borax (already measured out and placed in coffee filter) to glue water
mixture in Ziploc bag
8) Immediately seal bag and begin to mix the mixture with in the bag
9) Gently need and mix being sure to break up and Borax clumps
10) Knead and mix approximately 1 – 2 minutes
11) Remove your polymer from the bag. (may be sticky at first, but work and
squeeze it with your hands)
12) Discard any leftover liquid in bag
13) Store your polymer in 2nd Ziploc bag. Should last at least one month
SJK
Physical Science Polymers 7/29/2017
Page 1 of 3
So….. What exactly happened?
Explanation:
The Borax (Sodium tetrborate Na2B4O7 – H2O) is acting as a cross-linking agent or
connector for the glue molecule polymer chains Poly-vinyl acetate [C4H6O2]n.
The polymer chains that moved freely in the water can no longer move freely when
cross-linked and the polymer chains become bound together. Since the PVA chains can
no longer flow freely your polymer takes on the characteristics of Silly Putty.
PVA
Chain
The polymers in Silly Putty have covalent bonds within the molecules, but hydrogen
bonds between molecules. The hydrogen bonds are easily broken. When small amounts
of stress are slowly applied to the putty, only a few bonds are broken and the putty
“flows”. When larger amounts of stress is applied quickly, there are many hydrogen
bonds that break, causing the putty to tear or break
A dilatant is a substance that behaves or reacts differently to hard, fast pressure than it
does to slow, even pressure.
SJK
Physical Science Polymers 7/29/2017
Page 2 of 3
So… Let’s make some observations/PLAY…….
Activity Questions
Try the following activities to learn more about the properties of your polymer. Record
your results in the space provided.
1. Shape your polymer into a ball. Does it bounce?
2. Let the ball sit on the table. Describe what happens to it during the next 5 minutes.
3. Quickly poke your finger into the polymer on the table. What happens?
4. Try pulling some of your polymer between your hands. Does it stretch? Let go
and see if it will snap back.
5. Hold the polymer between your fingers and allow gravity to do its thing. What
happens?
6. What happens if you pull the polymer very hard quickly?
7. What is your conclusion about your polymer? Is it more like a liquid or more like
a solid?
Try some other activities that you can think of. Record what you find out. Have Fun!
SJK
Physical Science Polymers 7/29/2017
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