General Approaches to Polymer Synthesis

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

7. Polymerizability of Vinyl Monomers

8. Types of Vinyl Polymerization

9. Thermodynamics of Polymerization

10. Thermodynamics of Polymerization

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

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 Aqueous Phase: 16.6 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 contaminatedby surface active agents Coagulation introduces salts;Poor electrical properties

15. Components of Emulsion Polymerization R. Water soluble initiator

16. POLYMERS PRODUCED USING EMULSION PROCESSES

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 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 • ControlledFree Radical Polymerization • Broad range of monomers available • Accurate control of molecular weight • Mw/Mn  1.05 --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 (1939-1945) 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