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Introduction to PolymersIntroduction to Polymers

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Where are Polymers?Where are Polymers?

ENGINEERING Polymers:

improved strength and better

elevated temperature properties

COMMERCIAL Polymers:

used in large quantities

for their lightweight, corrosion-resistance

and good formability

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What is Polymer?What is Polymer?

Polymer in Greek roots = poly + meros

poly = many

meros = unitMany unit

Polymer: High molecular weight molecule

made up of a small repeat unit (monomer).

Examples: polypropylene, proteins, DNA

Monomer: Low molecular weight compound

that can be connected together to give a polymer

Examples: ethylene Polyethylene

Oligomer: Short polymer chain 2

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Types of polymersTypes of polymers

Classification by origin:

Natural polymers :

- polymers produced by living organisms.

- polysaccharides (starch, cellulose, gums etc),protein (gelatin, albumin, insulin, enzymes),

polyisoprenes (natural rubber) and nucleic acids

(RNA and DNA)

- biopolymers or biological macromolecules

Synthetic polymers

- plastics

- polyethylene, polypropylene, polystyrene,

polyester, nylon etc 3

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Classification by chain structureClassification by chain structure:

Linear polymer chain- polymer chain composed of a single

backbone with no branches

Branched polymer chain- polymer chain with one or more substituent

side chains or branches.

Cross-linked polymer- polymer chain is linked with another polymer

chain

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Thermoplastic

Thermoset

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Classification by monomer composition

Homopolymers: polymers are formed from a single type of monomer

Copolymers: polymers made up of 2 or more monomers

- Random copolymers:

monomers are randomly arranged within polymer chain

- Alternating copolymers:

monomers are alternately arranged within polymer chain

- Block copolymers:

large blocks of each monomer are arranged in polymer chain

- Graft copolymers:

one type of monomer is grafted to the long chain of another7

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Homopolymer

Copolymer

- Random copolymer

- Alternating copolymer

- Block copolymer

- Graft copolymer

A- B-

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Classification by polymerization mechanism

Addition or chain growth polymerization

- Polymerization in which monomers are linked together withoutthe splitting of a water or other simple molecules.

- 3 stages: initiation, propagation, and termination

- Examples: polyethylene, polypropylene

Condensation or step growth polymerization

- Polymerization in which polymers are formed through a

condensation reaction, releasing small molecules as by-products.

- Examples: polyester, polyamides

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Addition or chain growth polymerization:

1. Initiation: creates the active center on the first monomer

2. Propagation: an additional monomer adds to the growing chain

3.Termination: the active center is destroyed stopping the reaction

= initiator

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Condensation or step growth polymerization:

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Common PolyolefinsM ono m er o lym er

thylene

H 3 CC H 3

nRepeat unit

olyethylene

C H 3

C H 3

n

C H 3 C H 3 C H 3 C H 3 C H 3 C H 3C H 3

P ropylene

P olypropylene

P hC H 3

n

P h P h P h P h P h P hP hStyrene

P olystyrene

Cl

C H 3

n

C l C l C l C l C l C lC lVinyl C hloride

P oly(vinyl chloride)

F 2C C F2

Tetrafluoroethylene

F 3 C

F 2C

CF 2

F 2C

CF 2

F 2C

CF 2

F 2C

CF 2

F 2C

CF 2

F 2C

CF 2

C F 3n

P oly(tetrafluoroethylene ): T eflon

1

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Polyesters, Amides, and

UrethanesM on om er P o lym er C O 2HH O 2C

H OO H

O O

H O OH 2C

H 2C O

nTerephthalic

acid

Ethyleneglycol

Poly(ethylene terephthalate

H

Ester

H O O H

O O

4H 2N N H 24

Adipic Acid 1,6-Diaminohexane Nylon 6,6H O N

HNH

H

O O

4 4

n

C O 2HH O 2C

Terephthalicacid

N H 2H 2N

1,4 -Diamino

benzene

Kevlar

O

H O

OHN

HN H

n

Amide

H OO H

Ethyleneglycol

H 2CO C N N C O

4 ,4 -diisocyantophenylmethaneSpandex

H 2

C

H

N

H

N

O

H O

O

O

H 2

C

H 2

C O Hn

U rethane linkage1

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functional groups are specific groups ofatoms within molecules that

are responsible for the characteristic chemical reactions of those molecules

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-Combination: 2 chains combine together

-- Disproportionation: produces two different form of compounds,one more oxidized and one more reduced than the original

compound

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Typical Properties of PolymersTypical Properties of Polymers

Good chemical resistance at room temperature

Low density and Youngs modulus

Brittleness at low temperatures

Low strength and chemical resistance at high temperatures Processability at relatively low temperatures

Good insulators (except conductive polymers)

Transparent and good optical properties

Gas permeability

Recycling

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Polymer NomenclaturePolymer Nomenclature

Polymer types are named after the functional group linkage

in their backbone i.e. the bonds between the monomers.

Examples: Polyesters, polyethers, polyamides etc.

If more than one type of linkage is present then both figure in

the names, e.g. polyetherimide

The language (script):

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Most common naming process:

- poly(monomer), or

- poly(monomer1-co-monomer2)

- poly(monomer1-block-monomer2)- poly(monomer1-graft-monomer2)

IUPAC (International Union of Pure and Applied Chemistry)

nomenclature: rarely used in common literature, only as

referencesExample of a source-based polymer name:

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Examples of polymer nomenclature

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Classification by polymerization mechanism

Addition (chain) polymerization

Condensation (step) polymerization

Polymerization = a chemical process that combines several monomers

to form a polymer or polymeric compound

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Copolymer: polymer made up of 2 or more

monomers

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Classification by thermal behaviour

Thermoplastics

Thermosets

Thermoplastics (material

that is plastic ordeformable, melts to a

liquid when heated and

freezes to a brittle, glassy

state when cooledsufficiently), polystyrene,

polyethylene

Thermosets (cannot be

melted and remolded)

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Copolymer: polymer made up of 2 or more

monomers

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Typical Properties of PolymersTypical Properties of Polymers

Good chemical resistance at room temperature

Low density and Youngs modulus

Brittleness at low temperatures

Low strength and chemical resistance at hightemperatures

Processability at relatively low temperatures

Good insulators (except conductive polymers)

Transparent and good optical properties

Gas permeability Recycling

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PolymerClassifications

Thermoset: cross-linked polymer that

cannot be melted (tires, rubber bands)

Thermoplastic: Meltable plastic

Elastomers: Polymers that stretch and

then return to their original form: often

thermoset polymers

Thermoplastic elastomers: Elastic

polymers that can be melted (soles of tennis

shoes)

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very large molecules

(macromolecules) thatare comprised of smaller

unites or monomers.

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Polymer = poly + mer

poly = many

mer = unit

Many unit

Polymer: High molecular weight molecule made up

of a small repeat unit (monomer).

Monomer: Low molecular weight compound that can

be connected together to give a poymer

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Common PolyolefinsM ono m er P o lym er

thylene

H 3 CC H 3

nRepeat unit

P olyethylene

C H 3

C H 3

n

C H 3 C H 3 C H 3 C H 3 C H 3 C H 3C H 3P

ropylene

P olypropylene

P hC H 3

n

P h P h P h P h P h P hP hStyrene

P olystyrene

C lC H 3

n

C l C l C l C l C l C lC lVinyl C hloride

P oly(vinyl chloride)

F 2C C F2

Tetrafluoroethylene

F 3 C

F 2C

CF 2

F 2C

CF 2

F 2C

CF 2

F 2C

CF 2

F 2C

CF 2

F 2C

CF 2

C F 3n

P oly(tetrafluoroethylene ): T eflon

P l t A id d

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Polyesters, Amides, and

UrethanesM on om er P o lym er C O 2HH O 2C

H OO H

O O

H O OH 2C

H 2C O

nTerephthalic

acid

Ethyleneglycol

Poly(ethylene terephthalate

H

Ester

H O O H

O O

4H 2N N H 24

Adipic Acid 1,6-Diaminohexane Nylon 6,6H O N

HNH

H

O O

4 4

n

C O 2HH O 2C

Terephthalic

acid

N H 2H 2N

1,4 -Diamino

benzene

Kevlar

O

H O

OHN

HN H

n

Amide

H OO H

Ethyleneglycol

H 2CO C N N C O

4 ,4 -diisocyantophenylmethaneSpandex

H 2C

HN

HN

O

H O

O

OH 2C

H 2C O H

n

U rethane linkage

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Natural PolymersM o n o m e r Po lymer

Isoprenen

Polyisoprene:atural rubbe r

O

H

H O

H

H O

H

H

O HHO H

O H

Poly(- -glycoside):cellulose

O

H

O

H

H O

H

H

O HHO H

O H

H

n

- -glucose

H 3N

O

O Polyamino acid:protein

H 3 N

OHN

R 1

OHN

R n+ 1

O

O H

R n+ 2n

Am ino Acid

BaseO

O H

OP

O

O

O

oligonucleic acidN A

N ucleotide

Base = C, G , T, A

BaseO

O

OP

O

O

O

N A

N A

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Homopolymers: polymers formed from a single type of monomer


- Random copolymers: A and B randomly vary in chain

- Alternating copolymers: A and B alternate in polymer chain

- Block copolymers: large blocks of A alternate with large blocks of B

- Graft copolymers: chain of B grafted on to A blackbone

Terpolymers: polymers made up of 3 different types of monomers

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Homopolymers

Copolymers

- Random copolymers

- Alternating copolymers

- Block copolymers

- Graft copolymers

Terpolymers

A-C

-B-

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Homopolymers: polymers formed from a single type of monomer


- Random copolymers: A and B randomly vary in chain

- Alternating copolymers: A and B alternate in polymer chain

- Block copolymers: large blocks of A alternate with large blocks of B

- Graft copolymers: chain of B grafted on to A blackbone

A and B = monomers7

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Classification of polymersClassification of polymers

Origin

Chain structure

Thermal behaviour

monomer composition

polymerization mechanism

Documents

Teaching Test 28-11-09