1. Polymers Large molecules synthesized by bringing together many smaller molecules called monomers.

2. There are two main kinds of polymers. Type 1: Addition Polymers Each small molecule adds to the end of a growing chain. Polyethylene is an example Type 2: Condensation Polymers Monomer units come together with the elimination of some small molecule (often water). Polyesters and nylons are examples

3. Addition Polymers via Cationic Polymerization First let us look at a dimerization.

4. Addition Polymers via Cationic Polymerization Now let us look at a polymerization. Thousands of times more propene

5. Chain termination

6. 3. Chain termination Chain Reactions 1. Chain initiation 2. Chain propagation

7. Thousands of times more propene 1. Chain initiation 2. Chain propagation

8. 3. Chain termination

9. Polypropene or Polypropylene methyls all on same side. isotactic methyls alternate sides. syndiotactic methyls random atactic

10. Isotactic polypropylene atactic polypropylene “7 billion pounds in USA each year. Crystalline Melting point165ºC. Used for durable goods, appliances, autoparts, packaging, wraps for snack food, yarn,carpets, rope” “amorphous solid, low melting used for asphalt and sealants.”

11. Addition Polymers via Radical Polymerization Hydrogen peroxide Hydroxyl radical Hydroxyl radical A radical is a chemical species with an odd electron.

12. Addition Polymers via Radical Polymerization styrene Keep going for thousands of times. Gives polystyrene.

13. Polystyrene Typical molecular weights 100-150,000 9 billion pounds per year in USA. Used for injection molding for dining utensils, handles housewares, toys, cameras, etc. Expandable polystyrene foam. Uses a blowing agent (pentane) to form a foam. Used for packaging and coffee cups.

14. Other Addition Polymers

16. Cross linking

18. “a sticky mess” vulcanization Charles Goodyear