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CHM 585 / 490. Chapter 5. Chapter 5. Polystyrene PET Addition polymerization Condensation Polymerization. Polystyrene. How many “mers”. Monomer Dimer Trimer Oligomer Polymer. Polystyrene. Polystyrene. Dow polystyrene plants. Polystyrene is a vinyl polymer - PowerPoint PPT Presentation
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CHM 585 / 490
Chapter 5
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Chapter 5
• Polystyrene
• PET
• Addition polymerization
• Condensation Polymerization
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R. +
R
. R
.
R
.H2C CH( )
n
Polystyrene
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How many “mers”
• Monomer
• Dimer
• Trimer
• Oligomer
• Polymer
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R. +
R
. R
.
R
.H2C CH( )
n
Polystyrene
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Polystyrene
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Isotactic polypropylene
Syndiotactic polypropylene
Atactic Polypropylene
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Dow polystyrene plants
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• 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
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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
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Esterification
COOH
+ CH3CH2OH
OCH2CH3O
H2O+
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Esterification / Condensation
COOH
+ 2 CH3CH2OH
OCH2CH3O
2 H2O+
COOHO OCH2CH3
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COOHOCH2CH2OHO
2 H2O+
COOHO OCH2CH2OH
HO OH+ 2
OCH2CH2OHO
O OCH2CH2OH
COOH
COOH
+ 2
OCH2CH2OO
O OCH2CH2O
O
COOH
O
COOH
O
OCH2CH2O
O
)
( n
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O
EOOHHO
large excess of water
Ethylene glycol
+ 0.5 O2
O
EO
Ag catalyst
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Polyethylene TerephthalateCondensation Polymer
O
OCH2CH2O
O
)
( n
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Transesterification
O OCH3
+ CH3CH2OH
O OCH2CH3
+ CH3OH
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PET by Transesterification
O
OCH2CH2O
O
)
( n
O
OCH2CH2O
O
)
( n
O OCH3
+ CH3OH
OOCH3
HO OH+ 2
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PET by Transesterification
• DMT is a distillable material– Can be purified
• Melts at 140 C– Can be shipped and transferred as a liquid
CO2CH3
CO2CH3
DMT
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Catalysis
• Esterifications and transesterifications are acid catalyzed reactions.
• But!!!!!
• What else is an acid catalyzed reaction?
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Ether Formation
• Acid catalyzed dehydration of alcohols
2 ROH ROR + H2O
HO OH HO O OH
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PET catalysts
• Typically not:– H2SO4, H3PO4
• Common catalysts:– Zinc acetate, Sb2O3, Ti(OR)4
• Often combinations used
• Leave in catalyst
