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Polymers are very large molecules made of a chain of many smaller molecules bonded together.
The prefix “poly” means many.
The small molecules that are used to create polymers are called monomers .
The prefix
“mono” means one.
Most polymers are made of organic compounds that contain the elements carbon and hydrogen, but may also include other elements like oxygen and nitrogen.
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Polymers form when chemical bonds link large numbers of monomers together in a repeating pattern.
Think of polymers like chains of many paper clips connected together. This is why chemists often call them “polymer chains.” Each paper clip would represent a monomer molecule.
When two different monomers combine, they form a copolymer
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Elmer’s glue is a mixture of a polymer called polyvinyl acetate and water.
The long “chains” of the polymer can slide past each resulting in a viscous liquid.
Below is a picture of the chemical structure of a small section of the polyvinyl acetate chain:
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How does the glue become rubber?
 Step 1
When Borax, also known as Sodium Perborate
(Na2B4O7), dissolves in water, borate ions are formed in 2 successive reactions:
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How does the glue become rubber?
 Step 2
The borate ions react with the polyvinyl acetate to form polyvinyl alcohol.
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How does the glue become rubber?
 Step 3
The borate ions combine with the polyvinyl alcohol chains to link them together in cross-links.
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Why does the glue become rubber?
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1. Make a saturated solution of Borax in water.
2. Measure 5 ml of water in a cup, place a mark on the cup at the 5 ml level, and discard the water.
3. Pour Elmer’s white glue into the cup until it reaches the 5 ml mark you made in step 1.
4. Pour 20 ml of the Borax solution into the cup containing the glue-water mixture and stir.
5. After the material becomes like rubber, scrape it out and form it into a ball, squeezing out the excess liquid into a wastebasket.
The liquid glue has been transformed into a rubber ball by polymer cross-linking.
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