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

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

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

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  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. propene Thousands of times more

  5. Chain termination

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

  7. 1. Chain initiation propene Thousands of times more 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 “7 billion pounds in USA each year. Crystalline Melting point165ºC. Used for durable goods, appliances, autoparts, packaging, wraps for snack food, yarn,carpets, rope” atactic polypropylene “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

  15. Other Addition Polymers

  16. Cross linking

  17. “a sticky mess” vulcanization Charles Goodyear

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