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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

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general approaches to polymer synthesis
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

current strategies in polymer synthesis
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
free radical initiated polymerization
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
anatomy of addition polymerizations
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.
polymerizability of vinyl monomers
Polymerizability of Vinyl Monomers

Active Centers must be stable enough to persist though multiple monomer additions

  • Typical vinyl monomers
suspension polymerization
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
suspension polymerization of styrene
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

emulsion polymerization
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

components of emulsion polymerization
Components of Emulsion Polymerization

R.

Water soluble initiator

major developments in the 1950 60 s
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
ziegler natta metal coordinated polymerization
Ziegler-Natta (Metal-Coordinated) Polymerization
  • Stereochemical Control
  • Polydisperse products
  • Statistical Compositions and Sequences
  • Limited set of useful monomers, i.e. olefins
  • SINGLE SITE CATALYSTS
polyolefins
Polyolefins
  • Polypropylene (1954)
  • PP
  • dishwasher safe plastic ware, carpet yarn, fibers and ropes, webbing, auto parts
tacticity
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
additional developments in the 1980 s
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
free radical initiated polymerization22
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
genetic approaches via modified microorganisms
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
commodity polyolefins
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

commodity polyolefins25
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

commodity vinyl polymers
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

semi commodity polymers
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

commodity condensation polymers
Commodity Condensation Polymers

Nylon 6 /

bearings, molded parts

carpet yarn

marine rope

cooking/boiling bags

Nylon 66 (1939)

Fibers, tire cord, fishing line

commodity condensation polymers29
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