PolymerisationPolymerisation

Addition PolymerisationAddition Polymerisation

Condensation PolymerisationCondensation Polymerisation

Uses of polymersUses of polymers

Addition PolymerisationAddition Polymerisation

A carbon – carbon double bond is needed in A carbon – carbon double bond is needed in the monomerthe monomer

A monomer is the small molecule that makes A monomer is the small molecule that makes up the polymerup the polymer

C CH

H

H

Hn

ethene

high pressure/trace O2

catalyst C C

H

H

H

H npoly(ethene)

Addition PolymerisationAddition Polymerisation

The polymer is the The polymer is the onlyonly product product Involves the opening out of a double bondInvolves the opening out of a double bondThe conditions of the reaction can alter the The conditions of the reaction can alter the

properties of the polymerproperties of the polymerReaction proceeds by a free radical Reaction proceeds by a free radical

mechanismmechanismOxygen often used as the initiatorOxygen often used as the initiator

Addition polymerisationAddition polymerisation

The board specifies that you know this addition The board specifies that you know this addition polymerisation reactionpolymerisation reaction

C CH

H

H C

H

C C C

H H

H H H

Addition polymerisationAddition polymerisation

Conditions are high pressure and an Conditions are high pressure and an oxygen initiator (to provide the initial free oxygen initiator (to provide the initial free radical).radical).

Monomer = phenyletheneMonomer = phenylethenePolymer = poly(phenylethene)Polymer = poly(phenylethene)

Addition PolymerisationAddition Polymerisation

You are expected to be able to do the You are expected to be able to do the following things with addition polymers:following things with addition polymers:

Predict the repeating unit of the polymer Predict the repeating unit of the polymer given the monomergiven the monomer

Predict the monomer from the polymer – Predict the monomer from the polymer – displayed formula and even empirical displayed formula and even empirical formula.formula.

Know about stereochemistry of addition Know about stereochemistry of addition polymers.polymers.

Prediction the repeating unitPrediction the repeating unit

This is easy, basically open out the This is easy, basically open out the double bond. double bond.

C C

H

H

Cl

H

chloroethene

C C C C

H H H H

H HCl Cl

poly(chloroethene) aka polyvinylchloride (pvc)

Predicting the monomer from the Predicting the monomer from the polymerpolymer

This is kind of the opposite to what you This is kind of the opposite to what you have just done.have just done.

They may ask you to draw different They may ask you to draw different formulae. formulae.

You need to make sure you can convert You need to make sure you can convert repeating units into monomers, and draw a repeating units into monomers, and draw a ring around the repeating unitring around the repeating unit

Stereoisomerism in Addition Stereoisomerism in Addition polymers.polymers.

Ziegla and Natta in the 1950s cam up with Ziegla and Natta in the 1950s cam up with a way of controlling the repeating unit.a way of controlling the repeating unit.

They won a Joint Nobel prize for their workThey won a Joint Nobel prize for their workThe polymerisation process can be The polymerisation process can be

controlled used a tin/aluminium catalyst at controlled used a tin/aluminium catalyst at 50°C and 1.5atm 50°C and 1.5atm

Stereoisomerism in Addition Stereoisomerism in Addition polymers.polymers.

Previous to this only one type of Previous to this only one type of poly(ethene) could be made, called LDPE poly(ethene) could be made, called LDPE or low density poly(ethane). or low density poly(ethane).

The chains formed a tangled mass. The chains formed a tangled mass. HDPE could now be produced.HDPE could now be produced.This has a much stiffer structure due to This has a much stiffer structure due to

areas of crytallinity where the polymer areas of crytallinity where the polymer chains are much more ordered.chains are much more ordered.

Stereoisomerism in Addition Stereoisomerism in Addition polymers.polymers.

HDPE has a much higher boiling point due HDPE has a much higher boiling point due to these more ordered regions. to these more ordered regions.

Generally used to make plastic bottles.Generally used to make plastic bottles.Ziegler and Natta also discovered that Ziegler and Natta also discovered that

they could make stereo regular polymers. they could make stereo regular polymers. Isotactic, syndiotactic and atactic.Isotactic, syndiotactic and atactic.

Poly(propene) and stereoisomerismPoly(propene) and stereoisomerism

Isotactic. This is a very regular type of Isotactic. This is a very regular type of polymer chain. All the methyl groups are polymer chain. All the methyl groups are on the same side. on the same side.

H H H H H H H HCH3 CH3 CH3 CH3 CH3 CH3 CH3 CH3

Poly(propene) and stereoisomerismPoly(propene) and stereoisomerism

Syndiotactic. A slightly less regular but still very Syndiotactic. A slightly less regular but still very ordered polymer. ordered polymer.

The methyl groups alternate the side of chain The methyl groups alternate the side of chain they are on.they are on.

H H H HH H H

Poly(propene) and stereoisomerismPoly(propene) and stereoisomerism

Atactic. Atactic. This is a completely random allocation of This is a completely random allocation of

methyl groups along the carbon skeleton. methyl groups along the carbon skeleton.

H H HH HH H

Poly(propene) and stereoisomerismPoly(propene) and stereoisomerism

This varying degree of randomness will This varying degree of randomness will affect the strength and melting point of the affect the strength and melting point of the polymer. polymer.

The less random, the stronger the polymer The less random, the stronger the polymer and the higher the melting point and the higher the melting point

This is because in a more ordered polymer This is because in a more ordered polymer they chains can get closer together and they chains can get closer together and hence the van der Waal’s forces will be hence the van der Waal’s forces will be greater.greater.

Condensation PolymersCondensation Polymers

Involves 2 monomers that have different Involves 2 monomers that have different functional groups.functional groups.

They also involve the elimination of water or They also involve the elimination of water or another small molecule. another small molecule.

Hence the term Hence the term condensationcondensation polymer. polymer. Monomer A + Monomer B Monomer A + Monomer B Polymer + small Polymer + small

molecule (normally water).molecule (normally water). Common condensation polymers include Common condensation polymers include

polyesters (the ester linkage) and polyamides polyesters (the ester linkage) and polyamides (the amide linkage as in proteins).(the amide linkage as in proteins).

PolyestersPolyesters

The OCR example here is terylene, a polymer of The OCR example here is terylene, a polymer of benzene-1,4-dicarboxylic acid and ethane-1,2-benzene-1,4-dicarboxylic acid and ethane-1,2-diol.diol.

The ester linkage is formed between the The ester linkage is formed between the monomersmonomers

C

O

Othe ester linkage

PolyestersPolyesters

You need to be able to reproduce the formation You need to be able to reproduce the formation of terylene, and possibly predict the structures of of terylene, and possibly predict the structures of other polyestersother polyesters

HO C

O

C

O

OHn + HO CH2 CH2 OHn

heat with an acid catalyst

C

O

C

O

O CH2 CH2 O

poly(ethan-1,2-diyl benzene-1,4-dicarboxylate)

n

PolyamidesPolyamides

These involve the linkage of two monomers These involve the linkage of two monomers through the amide linkage as in proteins (e.g. through the amide linkage as in proteins (e.g. silk)silk)

C

O

N

Hthe amide linkage

Nylon 6,6 a polyamideNylon 6,6 a polyamide

N (CH2)6 NH

H

H

HC

O

OH(CH2)4

HO

OC

1,6-diaminohexane hexanedioic acid

N (CH2)6

H

N

H

C

O

(CH2)4 C

O

part of a nylon polymer chain

Kevlar a polyamideKevlar a polyamide

NH2H2N CO

HO(CH2)4 C

O

OH

N N C (CH2)4 C

OO

H H

part of the kevlar polymer chain

Uses of polyamidesUses of polyamides The main use of polyesters and polyamides is as The main use of polyesters and polyamides is as

fibres in clothing.fibres in clothing. Most clothing now has a degree of Most clothing now has a degree of

manufactured fibres woven into the natural manufactured fibres woven into the natural material (such as cotton). material (such as cotton).

This gives the material more desirable This gives the material more desirable characteristics, such as stretchiness, and better characteristics, such as stretchiness, and better washability.washability.

Don’t forget that proteins are also polyamides, Don’t forget that proteins are also polyamides, you must know how the linkage works with you must know how the linkage works with natural polymers such as proteins.natural polymers such as proteins.