1. General Approaches to Polymer Synthesis
1. Addition Chain Growth
Polymerization of Vinyl Monomers
Ring Opening Polymerization
Heterocylics
Metathesis of Cyclic Olefins
2. Condensation Step Growth
  Polymerization of A-B or AA/BB Monomers
3. Modification of Preformed Polymers
Polysaccharides
Peptides and Proteins
  Synthetic Precursors

2. Current Strategies in Polymer Synthesis
Objectives: Precise Macromolecular Design
1 . Control of: Molecular Weight
Molecular Weight Distribution
Composition
Sequence of repeat units
Stereochemistry
2.  Versatility

3. Free Radical Initiated Polymerization
Classical Free Radical Process
Applied to wide range of monomers
Broad scope of experimental conditions
Molecular weight can be controlled
Mw/Mn > 1.5  2.0 
Statistical compositions and sequences
Little stereochemical control

4. Anatomy of Addition Polymerizations
Initiation
Generation of active initiator
Reaction with monomer to form growing chains
Propagation
Chain extension by incremental monomer addition
Termination
Conversion of active growing chains to inert polymer
Chain Transfer
Transfer of active growing site by terminating one chain and reinitiating a new chain.

5. Polymerizability of Vinyl Monomers
Active Centers must be stable enough to persist though multiple monomer additions
Typical vinyl monomers

6. Polymerizability of Vinyl Monomers
Radical
Cationic
Anionic
Complex Metal
Ethylene + -
Propylene
+/-
1,1-Dialkyl olefins
1,2-Dialkyl olefins
1,3-Dienes
Styrenes

7. Polymerizability of Vinyl Monomers
Radical
Cationic
Anionic
Complex Metal
VCl + -
+/-
Vinyl esters
Acylates/ methacrylates
Acrylonitriles/ Acrylamides
Vinyl ethers
Substituted Styrenes

8. Types of Vinyl Polymerization
Method
Advantages
Disadvantages
Bulk (Neat)
Simple equipment
Rapid reaction
Pure polymer isolated
Heat buildup
Gel effect
Branched or crosslinked product
Solution
Good mixing
Ready for application
Lower mol. Wt.
Low Rpoly
Solvent Recovery
Suspension
(Pearl)
Low viscosity
Direct bead formation
Removal of additives
Emulsion
High Rpoly
Low Temperatures
High Mol. Wt.
High surface area latex
Coagulation needed
Latex stability
Inverse Emulsion
Water in oil latex formed
Inversion promotes dissolution in water

9. Thermodynamics of Polymerization

10. Thermodynamics of Polymerization
Monomer
-DHp, kJ/mole
-DSp,
J/K-mole
Tc, K (C)
Observed
Ethylene 93
155
600 (327)
400
MMA 56
104
478(205)
220
a-Methyl styrene 35
110
318 (45) 61
Isobutylene 48
121
326 ( 123) 50

11. Suspension Polymerization
Equivalent to a "mini-bulk" polymerization
Advantages
Aqueous (hydrocarbon) media provides good heat transfer
Good particle size control through agitation and dispersion agents
Control of porosity with proper additives and process conditions
Product easy to recover and transfer
Disadvantages
Suspending Agents contaminate product
Removal of residual monomer necessary

12. Suspension (Pearl) Polymerization
Process Type
Aqueous Phase
Monomers Used
Product
BEAD Polymer Soluble in Monomer
 1% Sol. Polymer Suspending Agents
Cu++ Inhibitors
Styrene Methyl Methacrylate Vinyl Acetate
Clear Beads
POWDER Polmer Insoluble in Monomer
Suspending Agents
Electrolytes
Vinyl Chloride Acrylonitrile Fluoroethylene
Opaque Beads or Powders
INVERSE Hydrocarbon Media
Monomer Initiator
Acrylamide Acrylic Acids
Beads  Emulsions

13. Suspension Polymerization of Styrene
Monomer Phase
16.6 Kg. Styrene (0.5 kg Methacrylic Acid)
0.012 kg AIBN
0.006 kg Benzoyl Peroxide
0.015 kg tert-Butyl Perbenzoate
Temp
Aqueous Phase: Kg of H2O
0.24 kg Ca3PO4
0.14 kg Na+ Naphthalene sulfonate
0.077 kg. 15% Sodium Polyacrylate
Polymerization Time. Hours

14. EMULSION POLYMERIZATION
Advantages:
High rate of polymerization
High molecular weights
Few side reactions High Conversion achieved
Efficient heat transfer
Low viscosity medium Polymer never in solution
Low tendancy to agglomerate
Emulsified polymer may be stabilized and used directly
Disadvantages:
Polymer surface contaminated by surface active agents
Coagulation introduces salts;Poor electrical properties

15. Components of Emulsion Polymerization
Water soluble initiator

16. POLYMERS PRODUCED USING EMULSION PROCESSES
Applications
Styrene-Butadiene Rubber (SBR)
Tires, Belting, Flooring,
Molded goods, Shoe soles, Electrical insulation
Butadiene-Acrylonitrile (nitrile rubber)
Fuel tanks, Gasoline hoses, Adhesives, Impregnated paper, leather and textiles
Acrylonitrile-Butadiene-Styrene (ABS)
Engineering plastics, household appliances,
Automobile parts, Luggage
Polyacrylates
Water based latex paints

17. Major Developments in the 1950-60's
Living Polymerization (Anionic)
Mw/Mn  1
Blocks, telechelics and stars available (Controlled molecular architecture)
Statistical Stereochemical Control
Statistical Compositions and Sequences
Severe functional group restrictions

18. Ziegler-Natta (Metal-Coordinated) Polymerization
Stereochemical Control
Polydisperse products
Statistical Compositions and Sequences
Limited set of useful monomers, i.e. olefins
SINGLE SITE CATALYSTS

19. Polyolefins Polypropylene (1954) PP
dishwasher safe plastic ware, carpet yarn, fibers and ropes, webbing, auto parts

20. Tacticity Isotactic Syndiotactic Heterotactic (Atactic)
All asymmetric carbons have same configuration
Methylene hydrogens are meso
Polymer forms helix to minimize substituent interaction
Syndiotactic
Asymmetric carbons have alternate configuration
Methylene hydrogens are racemic
Polymer stays in planar zig-zag conformation
Heterotactic (Atactic)
Asymmetric carbons have statistical variation of configuration

21. Additional Developments in the 1980's
"Immortal" Polymerization (Cationic)
Mw/Mn  1.05
Blocks, telechelics, stars
(Controlled molecular architecture)
Statistical Compositions and Sequences
Severe functional group restrictions

22. Free Radical Initiated Polymerization
Controlled Free Radical Polymerization
Broad range of monomers available
Accurate control of molecular weight
Mw/Mn  Almost monodisperse
Blocks, telechelics, stars
(Controlled molecular architecture)
Statistical Compositions and Sequences

23. Genetic Approaches via Modified Microorganisms
Monodisperse in MW
Monodisperse in Composition
Sequentially Uniform
Stereochemically Pure
Diverse set of functional groups possible through synthesis of novel amino acids

24. Commodity Polyolefins
Polyethylene
High Density (1954)
HDPE
Bottles, drums, pipe, conduit, sheet, film
Low Density ( )
LDPE
Packaging Film, wire and cable coating, toys, flexible bottles, house wares, coatings
Linear Low Density (1975)
Shirt bags, high strength films LLDE

25. Commodity Polyolefins
Polypropylene (1954) PP
dishwasher safe plastic ware, carpet yarn, fibers and ropes, webbing, auto parts
Polyisobutylene (1940)
PIB
inner tubes, flexible adhesives, raincoats

26. Commodity Vinyl Polymers
Polystyrene (1920) PS
Styrofoam, clear plastic cups
envelop windows, toys
Poly(vinyl chloride) (1927)
PVC
garden hose, pipe, car trim, seat covers, records, floor tiles

27. Semi-Commodity Polymers
Poly(methyl methacrylate) (1931)
PMMA
plexiglas, embedding resin, resist for X-ray applications
Polytetrafluoroethylene. (1943)
teflon, non stick cookware, no grease bearings,
pipe-seal tape

28. Commodity Condensation Polymers
Nylon 6 /
bearings, molded parts
carpet yarn
marine rope
cooking/boiling bags
Nylon 66 (1939)
Fibers, tire cord, fishing line

29. Commodity Condensation Polymers
Polyester (1941)
PET, dacron, mylar, kodel
fibers, film-backing, magnetic tapes, soft drink bottles, tire cord, moldings
Polycarbonate (1957)
PC, Lexan
shatter proof glass, cd-disks, car doors and roofs, appliance housings