Coordination Polymerization

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Coordination Polymerization
X
Rest of Chain
Catalyst
CH2 - CH
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Polyolefins
1950 - 1953
Ziegler-Natta Catalysts Metal Oxide Catalysts
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A Company Maker
The French can make even polyethylene look sexy!
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Ziegler and Natta
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Linear Polyethylene
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Into Court!
Can you polymerize propylene?
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The Many Uses of
Polypropylene
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Ziegler-Natta Catalysts
Insertion by the monometallic mechanism
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Ziegler-Natta Catalysts
Isotactic Addition
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Ziegler-Natta Catalysts
Syndiotactic Addition
Vacant Orbital
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Chain Polymerization Methods and Monomer Type
Not all monomers can be polymerized by a given
chain polymerization method. There is a
selectivity involved that depends upon chemical
structure (i.e. the inductive and resonance
characteristics of the group X in the vinyl
monomer shown opposite).
Rest of Chain
CH2 - C
CH2 CH
Active site
Rest of Chain
CH2 - CH -
CH2 - C
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Metallocenes A New Revolution?
1990s Metallocenes
1960s Metal oxide Z/N Catalysts
Technological Progress
1940s ICI-LDPE
A modern Exxon plant
Every 25 years or so, there
appears to be a quantum jump in
polyolefin technology. Metallocene catalysts are
considered by many to be
one such revolution in polymer science. They
have be referred to asdesigner catalysts,
because of their ability to
(co)polymerize an incredible variety of
polyolefins with different microstructures,
molecular weights and reproducible distributions
of molecular weight and branching.
1920s Staudinger
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Some Monomers that Can be Polymerized
Free Radically
Monomer
Chemical Structure
CH2 CH2
Ethylene
Tetrafluoro
CF2 CF2
-ethylene
Monomer
Chemical Structure
CH2 CH - CH CH2
Butadiene
Vinyl Chloride
Isoprene
Vinylidene
Chloride
Chloroprene
Vinyl Acetate
Styrene
Methyl
Methacrylate
Acrylonitrile
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Chain Polymerization Methods and Monomer Type
Some Monomers that can be Polymerized
Cationically
Monomer
Chemical Structure
d
d -
Isobutylene
CH2 CH X
Electron donating substituent
Styrene
Rest of Chain
CH2 - C
Vinyl Methyl
Ether
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Monomer
Chemical Structure
Monomers that can be Polymerized Anionically
Styrene
CH2 CH - CH CH2
Butadiene
COOCH3
Methyl
d
d -
-
Methacrylate
CH2 CH X
CH2 C-CH3
Electron withdrawing substituent
Acrylonitrile
Caprolactam
Rest of Chain
CH2 - C
Ethylene
Oxide
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Monomers that can be Polymerized using
Ziegler - Natta Catalysts
Ziegler - Natta catalysts are used to polymerize
a variety of a-olefins (e.g. ethylene and
propylene), but many polar monomers cannot be
polymerized this way as they inactivate the
initiator, either through complexation or
reaction with the metal components
X
Rest of Chain
Catalyst
CH2 - CH
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Polymerization Processes
We wont get into the details of laboratory
polymerizations or large scale reactor design,
but there are some basic things you should know.
TYPES

• Bulk
• Solution
• Suspension
• Emulsion

TWO USEFUL DISTINCTIONS

• Between batch and continuous
• Between single - phase and multi - phase

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Batch vs Continuous Depends on polymerization
time i.e. kinetics coming up next!
SINGLE - PHASE Bulk or Melt
Polymerization Solution Polymerization
MULTI - PHASE Gas / Solid
Liquid / Solid
Suspension Emulsion Etc
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Free Radical Suspension Polymerization
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Initiator - Water Insoluble Bead Size 5mm
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Free Radical Emulsion Polymerization
Micelles 10-3- 10-4 mm Monomer Droplets 1-10
mm Swollen Micelles 0.5mm
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