CHM 585 490 Chapter 5 1 Chapter 5

CHM 585 / 490 Chapter 5 1

Chapter 5 • • Polystyrene PET Addition polymerization Condensation Polymerization 2

Polystyrene 3

How many “mers” • • • Monomer Dimer Trimer Oligomer Polymer 4

Polystyrene 5

Polystyrene 6

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Dow polystyrene plants 11

• Polystyrene is a vinyl polymer • made from vinyl monomers; that is, small molecules containing carbon-carbon double bonds. • simplest vinyl polymer, polyethylene is made from ethylene 12

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Addition Polymerization • Addition polymerization if the entire monomer molecule becomes part of the polymer. • Polystyrene is made by an addition polymerization • Similarly polyethylene, polypropylene, and other vinyl polymers are addition polymers 14

Esterification 15

Esterification / Condensation 16

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Polyethylene Terephthalate Condensation Polymer 19

Transesterification 20

PET by Transesterification 21

PET by Transesterification • DMT is a distillable material – Can be purified • Melts at 140 C – Can be shipped and transferred as a liquid 22

Catalysis • Esterifications and transesterifications are acid catalyzed reactions. • But!!!!! • What else is an acid catalyzed reaction? 23

Ether Formation • Acid catalyzed dehydration of alcohols 24

PET catalysts • Typically not: – H 2 SO 4, H 3 PO 4 • Common catalysts: – Zinc acetate, Sb 2 O 3, Ti(OR)4 • Often combinations used • Leave in catalyst 25