1. “The World We Create” NATS 101 Section 6
Next Homework
Posted in D2L!
04/01

2. Polymer Transformations
How we change the materials that have changed society and beyond...
Polymer Transformations

3. These Transformations…?
The Big Picture Framework

4. Natural Polymers of Glucose (or modified glucose)
Transforming Polymers
Muscle Fuel: GLYCOGEN
Wood: CELLULOSE
All made from the monomer Glucose
Arthropod Exoskeletons: CHITIN
Plant Food: STARCH

5. Made by Transforming a Single Polymer
Transforming Polymers
Translucent Flexible Stable
Strong Dense Rigid
Ductile Flexible Degradable?
All made from the monomer Ethylene
High Tensile Strength Elastic
Degrade Resistant Flexible
Opaque Non-Permeable

6. We Can Not Duplicate Nature
Transforming Polymers
We Can Not Duplicate Nature
Why?
400
Vs.
4,000,000,000
4 Hundred Years of Chemistry
Vs.
4 Billion Years of Evolution
Nature inspires us, but is much too complex and subtle to mimic.
Scientist have had to develop methods that differ from nature.

7. A Simple Demonstration:
Transforming Polymers
A Simple Demonstration:
We start with a clear liquid polymer
We combine with an additive
We get a slimy goo (yes, “goo” is a technical term)
What happened in the beaker?

8. A simple demonstration:
Transforming Polymers
A simple demonstration:
What Happened? n
Polymer: Polyvinyl Alcohol (PVA) Small Section of Two Chains Shown n

9. A simple demonstration:
Transforming Polymers
A simple demonstration:
Weak Crosslinks Formed n
Additive: Borax (Sodium tetraborate decahydrate) Forms bonds, linking chains
Notice the dashed lines: |||||||| These represent a weaker interaction than Covalent Bonding. n

10. Tires Transformed Society
Vulcanization:
Tires Transformed Society
When sulfur and heat is added to rubber, the sulfur bonds to the polymer forming covalent crosslinks...

11. Vulcanization: How would this change the properties of the rubber?
When sulfur and heat is added to rubber, the sulfur bonds to the polymer forming covalent crosslinks.
How would this change the properties of the rubber?
Sulfur chain length can differ – what part of a tire should get the longer and shorter chains?
Tread?
Sidewalls?

12. Bouncing Balls: A different additive perhaps?
Two balls are composed of the same polymer
One is much more elastic
How is this achieved?
A different additive perhaps?
Now it’s your turn with the balls…

13. Transforming Polymers
Bouncing Balls:
Part I:
Follow the directions on your worksheet to transform a liquid polymer into an elastic ball.
Add the Borax slowly to the glue and observe the changes.
Part II:
Perform a bounce test by dropping your ball from the top of a meter stick and observing the height of the bounce.
Report your results to your TA.

14. Transforming Polymers
Bouncing Balls:
What Happened?
Crosslinker: Borax
Polymer: Polyvinyl Acetate (PVAc)

15. A Few Additives Used to Change Polymer Properties:
Transforming Polymers
Plasticizers: Used to soften polymers e.g. Phthalates Fillers: Used to strengthen a polymer
e.g. Inert materials like cellulose and asbestos
Stabilizers: Used to reduce polymer degradation e.g. Antioxidants, UV absorbers
Flame Retardants: Used to reduce combustibility
e.g. Halogens (Cl and F atoms)
Colorants: Used to provide color
e.g. Pigments (insoluble/opaque) and Dyes (soluble/transparent)

16. Polymer Structure Review:
Linear chains:
Crosslinked chains:
Branched chains:
NEW:
Copolymers:
…form when different “mers” are used to form a polymer. Can be linear, branched, etc… e.g.: Nylon

17. Transforming the Environment
BPA: What’s the Deal?
Water bottles were being made using copolymers of carbonate and BPA…
BPA (Bisphenol A) is not an additive here – it combines with carbonate monomers to form a copolymer. This adds strength and chemical stability to carbonate alone.
Next Week: Why this may be a problem...