1. Polymers: Giants Among Molecules

2. Chapter 102 Macromolecules Compared to other molecules, they are enormous –Molar mass: 10,000–1,000,000+ g/mol –Not visible to naked eye Polymers: made from smaller pieces –Monomer: small chemical building block Polymerization: process in which monomers are converted to polymers

3. Chapter 103 Natural Polymers Found extensively in nature –Life could not exist without polymers –Come in various shapes and sizes Made of sugars, amino acids, nucleic acids Examples: wool, silk, cotton, wood, paper

4. Chapter 104 Some Naturally Occurring Polymers

5. Chapter 105 Celluloid React cellulose with nitric acid Used for first films and billiard balls Highly flammable –Used in smokeless gunpowder No longer in use

6. Chapter 106 Synthetic Polymers Made from monomer synthesized from fossil fuels First manufactured shortly before World War II Synthesized using addition reactions –Add monomer to end of polymer chain –Build very large polymers

7. Chapter 107 Polyethylene Cheapest and simplest synthetic polymer –Made from CH 2 =CH 2 –Invented shortly before World War II Has two forms –High-density polyethylene (HDPE) –Low-density polyethylene (LDPE)

8. Chapter 108 Polypropylene Change a –H to –CH 3 Harder and has higher melting point than polyethylene

9. Chapter 109 Polystyrene Change a –H to benzene ring Widely used –Disposable cups –Insulation

10. Chapter 1010 Vinyl Polymers Change a –H to –Cl Tough thermoplastic –Polyvinyl chloride (PVC)

11. Chapter 1011 Teflon Change all –H to –F –C–F very strong. Resists heat and chemicals –Makes very unreactive polymer

12. Chapter 1012 Other Polymers

13. Chapter 1013 Practice Problems

14. Chapter 1014 Rubber Pre–World War II –Came from natural sources in S.E. Asia –Japan cut off supply during World War II Made of isoprene Chemists learned to make it during World War II

15. Chapter 1015 Vulcanization Link individual polymer strands with S atoms Makes rubber stronger –Can be used on natural or synthetic rubber Elastomers: materials that stretch and snap back –Key property of rubber

16. Chapter 1016 Synthetic Rubber Use butadiene –CH 2 =CH-CH=CH 2 Polychloroprene: substitute –Cl for a –H Change the properties for other uses –Tend to be resistant to chemicals

17. Chapter 1017 Copolymerization Add two or more different monomers Uses addition reaction Allows for modification of polymer’s properties Styrene–butadiene rubber (SBR) –75% butadiene/25% styrene mix –Used mainly for tires

18. Chapter 1018 Condensation Polymers Part of the monomer will not be incorporated into the final material –Typically a small molecule like water Formula of the repeating unit not same as monomer Used to produce nylon and polyesters

19. Chapter 1019 Composite Materials Use high-strength polymers –Could include glass, graphite, or ceramics Hold everything together with polymers –Typically thermosetting, condensation polymer Result is a very strong, lightweight material –Used in cars, sports gear, boats

20. Chapter 1020 Silicone Polymers Based on alternating Si and O atoms Heat stable and resistant to most chemicals Properties depend on length of polymer Many uses –Shoe polish, coatings on raincoats, Silly Putty

21. Chapter 1021

22. Chapter 1022 Properties of Polymers Crystalline: polymers line up –High tensile strength –Make good synthetic fibers Amorphous: polymers randomly oriented –Make good elastomers Some material has both types of polymers mixed together –Flexibility and rigidity

23. Chapter 1023 Fiber-Forming Properties Majority of fabrics made of synthetic polymers Tend to last longer, easier to care for –Nylon vs. silk Also may make mixtures –Cotton/polyester blends

24. Chapter 1024 Disposal of Plastics Do not degrade readily –Designed to be durable –Last a long time Make up 8% by mass of landfills –But make up 21% by volume –Tend to fill up landfills

25. Chapter 1025 Recycling Collect, sort, chop, melt, and then remold plastic Requires strong community cooperation

26. Chapter 1026 Plasticizers Make plastic more flexible and less brittle –Lower T g –Tend to be lost as plastic ages Most common plasticizers today based on phthalic acid

27. Chapter 1027 End of Chapter 10