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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


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


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 polymerization
Free Radical Initiated Polymerization

  • Controlled Free 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


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


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


Step growth or condensation polymerizations
Step-Growth or Condensation Polymerizations

Molecular Weight predicted by Carothers Equation:

A-A + B-B -[A-B-]x + x C

[A-A] = [B-B] = No

# of functional groups remaining at anytime = N

Extent of reaction = p

No - N

p = _____ or N = No (1 - p)

No

Degree of Polymerization, D.P. = No / N = 1 / (1 - p)


Problems in achieving high d p
Problems in Achieving High D. P.

1. Non-equivalence of functional groups

a. Monomer impurities

1. Inert impurities (adjust stoichiometry)

2. Monofunctional units terminate chain

b. Loss of end groups by degradation

c. Loss of end groups by side reactions with media

d. Physical losses

e. Non-equivalent reactivity

f. Cyclization

. Unfavorable Equilibrium Constant


Impact of percent reaction p on dp
Impact of percent reaction, p, on DP

Degree of Polymerization, D.P. = No / N = 1 / (1 - p)

Assuming perfect stoichiometry

DPmax= (1 + r) / (1 - r) where r molar ratio of reactants

if r = [Diacid] / [diol] = 0.99, then DPmax= 199


Cyclization
Cyclization

1. Thermodynamic stability

Rings of: 3,4,8 < 11 < 7, 12 << 5 << 6

2. Kinetic Control

Propagation more rapid than cyclization

Reduce probability of collision for rings 12

Non-reversible propagation process


Equilibrium in polyesterification
Equilibrium in Polyesterification

Reaction in closed system

p = fraction esterified


Equilibrium in polyesterification1
Equilibrium in Polyesterification

Effect of Keq on extent of reaction and DP

transesterification

esterification

amide formation




Preparation of aromatic polyesters
Preparation of Aromatic Polyesters

Stoichiometry and DP controlled by extent of glycol removed.



Polyamides via condensation nylon 66
Polyamides via Condensation -- Nylon 66

mp. 265C, Tg 50C, MW 12-15,000

Unoriented elongation 780%


Types of condensation polymers
Types of Condensation Polymers

Polyesters

Polyanhydrides

Polyacetals

Polycarbonates


Lexan polycarbonate
Lexan Polycarbonate

Interfacial Process

Tm = 270C,

Tg = 145-150C

10-40 % Crystalline,

Brittle Temp. - 10C

Ester Interchange

No Solvent, Pure Polymer with MW > 30,000 Formed


Types of condensation polymers1
Types of Condensation Polymers

polyurethanes

polyphenylene oxide

polyarylenes

polyarylene ether sulfones


Low temperature condensation polymerization
Low Temperature Condensation Polymerization

  • Interfacial or Solution in Polar Aprotic Solvents


Interfacial or solution polymerization in polar aprotic solvents con t
Interfacial or Solution Polymerization in Polar Aprotic Solvents (Con’t)


Applications of low temperature condensations
Applications of Low Temperature Condensations

  • Prep. of Infusible Thermally Stable Polymers

  • Prep. of Thermally Unstable Polymers

Prep. of Polymers Containing Functional Groups with Differing Reactivity

Formation of Block or Ordered Polymers

(No equilibration of polymer in melt allowed)

Direct Production of Polymer Solutions for Coatings, Spinning into Fibers, Solvent Blending to form Composites


Types of condensation polymers2
Types of Condensation Polymers

polyamides

polyimides

polybenzthiazoles

polybenzoxazoles


Aromatic polyamides aramids
Aromatic Polyamides “Aramids”

M-isomers favor formation of soluble polymers

Unique solvent combination

Can be Dry Spun to Fiber

As Spun:

Elongation, 23-34%,

Tenacity, 4.6-5.3 g/Denier

M.p. > 350 C

70% Strength Retained in Ionizing Radiation

Nomex


Polyimides for electronic applications
Polyimides for Electronic Applications

Fabricate in soluble form

Post treat to final form

Kevlar


Polyethersulfones
POLYETHERSULFONES

Bis-nucleophile

Polymerize by SnAr2

Monofunctional terminator to stabilize polymer

Use Temperature -100 to + 175C

Stable in air to 500C, Self Extinguishing

Molecular Weight = 65,000 - 250,000

Amorphous Material, Tg  200C, Films pressed at 280C


Polyphenylene oxide ppo
Polyphenylene Oxide (PPO)

Oxidative Coupling Process

Mn 30,000 to 120,000

Amorphous , Tg  210C Crystalline, Tm  270C

Brittle point  -170C

Thermally Stable to  370C

Noryl is a blend with polystyrene


Noryl is unique blend
Noryl is Unique Blend

  • Single Phase, Tg dependent upon composition

  • Maximum tensile strength at 80 wt% PPO

  • Other properties; volume fraction weighted average

  • Blend compatible with rubber modified polystyrene (high impact resistance)

  • Applications of Noryl Engineering Thermoplastics

  • Useful properties

  • High impact resistance

  • Flame retardant

  • High chemical stability

  • Low moisture absorbance (0.07%0

  • Use in appliance housings

  • Automobile dashboards

  • Radomes, fuse boxes, wiring splice devises


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