General Approaches to Polymer Synthesis

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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 Polysaccharides Peptides and Proteins   Synthetic Precursors

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

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Free Radical Initiated Polymerization Classical Free Radical Process Applied to extensive variety of monomers Broad extent of test conditions Molecular weight can be controlled Mw/Mn > 1.5  2.0  Statistical arrangements and groupings Little stereochemical control

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Anatomy of Addition Polymerizations Initiation Generation of dynamic initiator Reaction with monomer to frame developing chains Propagation Chain expansion by incremental monomer expansion Termination Conversion of dynamic developing chains to latent polymer Chain Transfer of dynamic developing site by ending one chain and reinitiating another chain.

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Polymerizability of Vinyl Monomers Active Centers must be sufficiently steady to endure however various monomer augmentations Typical vinyl monomers

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Polymerizability of Vinyl Monomers

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Polymerizability of Vinyl Monomers

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Types of Vinyl Polymerization

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Thermodynamics of Polymerization

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Thermodynamics of Polymerization

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Suspension Polymerization Equivalent to a "mini-bulk" polymerization Advantages Aqueous (hydrocarbon) media gives great warmth exchange Good molecule estimate control through fomentation and scattering specialists Control of porosity with appropriate added substances and process conditions Product simple to recuperate and exchange Disadvantages Suspending Agents pollute item Removal of remaining monomer essential

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Suspension (Pearl) Polymerization

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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

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EMULSION POLYMERIZATION Advantages: High rate of polymerization High sub-atomic weights Few side responses High Conversion accomplished Efficient warm exchange Low consistency medium Polymer never in arrangement Low tendancy to agglomerate Emulsified polymer might be balanced out and utilized straightforwardly Disadvantages: Polymer surface tainted by surface dynamic specialists Coagulation presents salts;Poor electrical properties

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Components of Emulsion Polymerization R . Water solvent initiator

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POLYMERS PRODUCED USING EMULSION PROCESSES

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Major Developments in the 1950-60's Living Polymerization (Anionic) Mw/Mn  1 Blocks, telechelics and stars accessible (Controlled sub-atomic design) Statistical Stereochemical Control Statistical Compositions and Sequences Severe useful gathering confinements

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Ziegler-Natta (Metal-Coordinated) Polymerization Stereochemical Control Polydisperse items Statistical Compositions and Sequences Limited arrangement of helpful monomers, i.e. olefins SINGLE SITE CATALYSTS

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Polyolefins Polypropylene (1954) PP dishwasher safe plastic product, cover yarn, filaments and ropes, webbing, vehicle parts

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Tacticity Isotactic All hilter kilter carbons have same arrangement Methylene hydrogens are meso Polymer frames helix to minimize substituent association Syndiotactic Asymmetric carbons have exchange setup Methylene hydrogens are racemic Polymer remains in planar crisscross compliance Heterotactic (Atactic) Asymmetric carbons have measurable variety of design

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Additional Developments in the 1980's "Immortal" Polymerization (Cationic) Mw/Mn  1.05 Blocks, telechelics, stars (Controlled sub-atomic engineering) Statistical Compositions and Sequences Severe useful gathering confinements

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Free Radical Initiated Polymerization Controlled Free Radical Polymerization Broad scope of monomers accessible Accurate control of sub-atomic weight Mw/Mn  1.05 - Almost monodisperse Blocks, telechelics, stars (Controlled sub-atomic design) Statistical Compositions and Sequences

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Genetic Approaches by means of Modified Microorganisms Monodisperse in MW Monodisperse in Composition Sequentially Uniform Stereochemically Pure Diverse arrangement of useful gatherings conceivable through combination of novel amino acids

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Commodity Polyolefins Polyethylene High Density (1954) HDPE Bottles, drums, pipe, channel, sheet, film Low Density (1939-1945) LDPE Packaging Film, wire and link covering, toys, adaptable containers, house products, coatings Linear Low Density (1975) Shirt sacks, high quality movies LLDE

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Commodity Polyolefins Polypropylene (1954) PP dishwasher safe plastic product, cover yarn, strands and ropes, webbing, car parts Polyisobutylene (1940) PIB internal tubes, adaptable cements, waterproof shells

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Commodity Vinyl Polymers Polystyrene (1920) PS Styrofoam, clear plastic mugs encompass windows, toys Poly(vinyl chloride) (1927) PVC plant hose, pipe, auto trim, situate covers, records, floor tiles

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Semi-Commodity Polymers Poly(methyl methacrylate) (1931) PMMA plexiglas, installing sap, oppose for X-beam applications Polytetrafluoroethylene. (1943) teflon, non stick cookware, no oil direction, pipe-seal tape

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Commodity Condensation Polymers Nylon 6/ course, formed parts cover yarn marine rope cooking/bubbling sacks Nylon 66 (1939) Fibers, tire string, angling line

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Commodity Condensation Polymers Polyester (1941) PET, dacron, mylar, kodel strands, film-backing, attractive tapes, soda pop jugs, tire rope, moldings Polycarbonate (1957) PC, Lexan smash verification glass, album circles, auto entryways and rooftops, machine lodgings

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