Chapter 26
Synthetic Polymers
26-00-03T01

Labeled
Title
 Addition Polymers
Caption
 Table 26-1 Important Addition Polymers
Notes
 The chain-growth mechanism involves addition of the reactive end of the growing chain across the double bond.
Keywords
 addition polymer
26-00-05UN

Labeled
Title
 Mechanism of Free Radical Polymerization
Caption
 In the first step of the reaction the initiator reacts with the monomer to start the chain. Another molecule of monomer adds to the chain in the propagation step.
Notes
 Chain growth may continue with addition of several hundred or several thousand styrene units.
Keywords
 free radical polymerization, initiator, propagation
26-00-06UN

Labeled
Title
 Mechanism of Free Radical Polymerization
Caption
 In the first step of the reaction the initiator reacts with the monomer to start the chain. Another molecule of monomer adds to the chain in the propagation step.
Notes
 Chain growth may continue with addition of several hundred or several thousand styrene units.
Keywords
 free radical polymerization, initiator, propagation
26-01

Labeled
Title
 Chain Branching
Caption
 Figure 26-1 Chain branching occurs when the growing end of a chain abstracts a hydrogen atom from the middle of a chain. A new branch grows off the chain at that point.
Notes
 Branching makes the polymer soft.
Keywords
 branching, polymer
26-01-01UN

Labeled
Title
 Mechanism of Cationic Polymerization
Caption
 Cationic polymerization occurs by a mechanism similar to the free-radical process, except that it involves carbocation intermediates.
Notes
 Strongly acidic catalysts are used to initiate cationic polymerization. BF3 is particularly effective catalyst, requiring a trace of water or methanol as a co-catalyst.
Keywords
 polymerization, boron trifluoride
26-01-02UN

Labeled
Title
 Mechanism of Cationic Polymerization
Caption
 Cationic polymerization occurs by a mechanism similar to the free-radical process, except that it involves carbocation intermediates.
Notes
 Strongly acidic catalysts are used to initiate cationic polymerization. BF3 is particularly effective catalyst, requiring a trace of water or methanol as a co-catalyst.
Keywords
 polymerization, boron trifluoride
26-02

Labeled
Title
 Good and Poor Monomers for Cationic Polymerization
Caption
 Figure 26-2 Cationic polymerization requires formation of a relatively stable carbocation intermediate.
Notes
 Chain branching occurs in cationic polymerization.
Keywords
 carbocation
26-02-01UN

Labeled
Title
 Anionic Polymerization
Caption
 Anionic polymerization occurs through carbanion intermediates.
Notes
 Effective anionic polymerization requires a monomer that gives a stabilized carbanion when it reacts with the anionic end of the growing chain.
Keywords
 anion, carbanion
26-02-02UN

Labeled
Title
 Mechanism of Anionic Polymerization
Caption
 Anionic polymerization is started by strong carbanion-like reagents such as an organolithium or Grignard reagent. Conjugate addition of the initiator to a monomer molecule starts the growth of the chain.
Notes
 Under these conditions there is no proton source available, and many monomer units reacts before the carbanion is protonated.
Keywords
 organolithium, Grignard reagent, monomer
26-02-03UN

Labeled
Title
 Mechanism of Anionic Polymerization
Caption
 Anionic polymerization is started by strong carbanion-like reagents such as an organolithium or Grignard reagent. Conjugate addition of the initiator to a monomer molecule starts the growth of the chain.
Notes
 Under these conditions there is no proton source available, and many monomer units reacts before the carbanion is protonated.
Keywords
 organolithium, Grignard reagent, monomer
26-03

Labeled
Title
 Stereochemistry of Polymers
Caption
 Figure 26-3 Three stereochemical types of addition polymers.
Notes
 Depending on the stereochemistry of addition, a polymer can be isotactic, syndiotactic, or atactic.
Keywords
 isotactic, syndiotactic, atactic
26-04

Labeled
Title
 Vulcanization
Caption
 Figure 26-4 Vulcanization of rubber introduces disulfide cross-links between the polyisoprene chains.
Notes
 Cross-linking forms a stronger, elastic material that does not pull apart when it is stretched.
Keywords
 vulcanization, disulfide links, cross-linking
26-04-01UN

Labeled
Title
 Synthetic Rubber
Caption
 The simplest form of rubber is a polymer of 1,3-butadiene.
Notes
 This polymer has properties similar to those of natural rubber, and it can be vulcanized in the same way.
Keywords
 rubber, vulcanization
26-04-03UN

Labeled
Title
 Copolymers of Two or More Monomers
Caption
 Many polymeric materials are copolymers, made by polymerizing two or more different monomers together.
Notes
 When a mixture of vinyl chloride and vinylidene chloride is induced to polymerize, the growing chain preferentially adds the monomer that is not at the end of the chain.
Keywords
 copolymers, vinyl chloride, vinylidene chloride
26-04-05UN

Labeled
Title
 Synthesis of Nylon 6,6
Caption
 Nylon is the common name for polyamides. The most common polyamide is called nylon 6,6 diamine.
Notes
 Molten nylon is cast into a solid shape or extruded through a spinneret to produce a fiber.
Keywords
 polyamides, nylon 6,6
26-04-06UN

Labeled
Title
 Nylon 6
Caption
 Nylon can also be made from a single monomer having an amino group at one end and an acid at the other.
Notes
 The reaction is similar to the polymerization of a-amino acids to give proteins.
Keywords
 nylon 6
26-04-07UN

Labeled
Title
 Polyesters
Caption
 The most common polyester is Dacronš, the polymer of terephthalic acid with ethylene glycol.
Notes
 When the reaction is heated, methanol is evolved, driving the reaction to completion.
Keywords
 polyester, terephthalic acid, ethylene glycol
26-04-09UN

Labeled
Title
 Polycarbonates
Caption
 Condensation of phosgene with a molecule of bisphenol A produces a polycarbonate ester.
Notes
 Bisphenol A is a common intermediate in polyester and polyurethane synthesis.
Keywords
 polycarbonate, carbonate ester phosgene
26-04-12UN

Labeled
Title
 Polyurethanes
Caption
 A polyurethane results when a diol reacts with a diisocyanate, a compound with two isocyanate groups.
Notes
 A stiffer polyurethane foam may be obtained by adding a small amount of glycerol to the polymerization mixture.
Keywords
 polyurethane, diol, diisocyanate
26-05

Labeled
Title
 Crystallinity
Caption
 FIgure 26-5 Crystallites are areas of crystalline structure within the large mass of a solid polymer.
Notes
 A highly regular polymer that packs well into a crystal lattice will be highly crystalline, and it will generally be denser, stronger, and more rigid that a similar polymer with a lower degree of crystallinity.
Keywords
 crystallites, crystallinity, crystal lattice
26-06

Labeled
Title
 Thermal Properties of Polymers
Caption
 Figure 26-6 Crystalline and amorphous long-chain polymers show different physical properties when they are heated.
Notes
 Long-chain polymers with low crystallinity are called amorphous polymers. Highly crystalline polymers become flexible and moldable when heated; amorphous polymers become become rubbery when heated above the glass transition temperature.
Keywords
 amorphous polymers, crystalline polymers, glass transition temperature
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