1. Chapter 29 Organic Chemistry Synthetic Polymers 6th Edition
Paula Yurkanis Bruice

2. A polymer is a large molecule made by linking together
repeating units of small molecules called monomers:

3. Chain-growth polymers, also known as addition polymers, are made by chain reactions:

4. Step-growth polymers, also called condensation
polymers, are made by combining two molecules while
removing a small molecule:

5. Chain-Growth Polymers
Chain-growth polymers proceed by one of three
mechanisms:
• Radical polymerization
• Cationic polymerization
• Anionic polymerization

7. Radical Polymerization

10. The molecular weight of the polymer can be controlled by
a process known as chain transfer:

11. Chain-growth polymerization of monosubstituted
ethylenes exhibits a marked preference for head-to-tail
addition:

12. Head-to-tail addition of a substituted ethylene results in a
polymer in which every other carbon bears a substituent:

13. Head-to-tail addition is favored for steric reasons.
Groups that stabilize radicals also favor head-to-tail
addition.

16. Branching of the Polymer Chain

17. Branched polymers are more flexible

18. Cationic Polymerization

21. The carbocation intermediates formed during
polymerization can undergo rearrangement to form more
stable carbocations:

22. Monomers with electron-donating substituents readily undergo cationic polymerization:

23. Anionic Polymerization
The initiator is a nucleophile, generally a strong base

24. Nonterminated chains are called “living polymers” and remain active until they are “killed.”

26. An Example of Anion Polymerization

27. What Determines the Mechanism?
Alkenes with substituents that can stabilize radicals
readily undergo radical polymerization.
Alkenes with electron-donating substituents that can
stabilize cations undergo cationic polymerization.
Alkenes with electron-withdrawing substituents that can stabilize anions undergo anionic polymerization.
Some alkenes undergo polymerization by more than one mechanism.

28. Ring-Opening Polymerization

30. Stereochemistry of Polymerization
Substituents on the same side:
Substituents regularly alternate on both sides:
Substituents in an atactic polymer are randomly oriented

31. Long, unbranched polymers with either isotactic or the
syndiotactic configuration can be prepared using an
aluminum–titanium initiator (Ziegler–Natta catalyst):

33. Polymerization of Dienes

34. Synthesis of Synthetic Rubber

35. The product resulting from polymerization of different
monomers is called a copolymer:

36. Four Types of Copolymers

37. Progress of a Step-Growth Polymerization

38. Nylon 6 is an example of a step-growth polymer formed
by a monomer with two different functional groups:

39. The incorporation of aromatic rings into polymers
improves the physical strength of the polymers:

41. Polyesters are step-growth polymers in which the
monomer units are joined together by ester groups:

42. Polyesters with two ester groups bonded to the same
carbon are known as polycarbonates:

43. Epoxy resins are the strongest adhesive known:

44. A urethane (carbamate) is a compound that has an
OR group and an NHR group bonded to the same
carbonyl compound:

45. Thermosetting Polymers
Very strong and rigid materials can be obtained by
cross-linking.

46. Oriented Polymers
These polymers are stronger than steel and can conduct electricity

47. Biodegradable Polymers
These polymers can be broken into small molecules by microorganisms
The cyclic dimer of lactic acid undergoes ring-opening polymerization to afford a high-molecular-weight polylactide:
Polyhydroxyalkanoates (PHAs) are condensation polymers of 3-hydroxycarboxylic acids:

48. Other Polymers
Thermoplastic polymers have both ordered crystalline regions and amorphous, noncrystalline regions.
Elastomers are polymers that stretch and then revert to the original shape.
Plasticizer is an organic compound that is added to a polymer to make it more flexible.

49. Dental Restorative Resin Components
Photo-curable resin used by dentists to restore decayed teeth
Bisphenol A linker
Bisphenol A may be hazardous to humans

50. Photo-Initiator Components

51. Photo-Initiation Process
A blue LED light is used to initiate polymerization

52. Radical-Initiated Polymerization
Curing is complete in 12 seconds