POLYMERS

POLYMERS

Addition polymers

Condensation polymers

Some definitions

Polymer

long chain molecule made from lots of small molecules joined together

Monomer

small molecules that join together in polymerisation

Addition Polymerisationformation of long chain molecules from lots of small

molecules joining together – with no other product

Condensation Polymerisationformation of long chain molecules from lots of small

molecules joining together – with a small molecule (e.g. water) released

http://users.argonet.co.uk/users/hoptonj/polymer.htm

Addition polymers

Addition polymers

H

C C

H

HH

H

C

H H

H

C

n

n

ethene poly(ethene)

polythene

Addition polymers

n

phenylethene poly(phenylethene)

H

C C

C6H5

HH

H

C

H H

C6H5

C

n

polystyrene

Addition polymers

n

methyl 2-propenoate poly(methyl 2-propenoate )

perspex

H

C

H COOCH3

CH3

Cn

H

C C

CH3

COOCH3H

Addition polymers

n

methyl 2-cyanopropenoate

superglue

H

C C

CN

COOCH3H

H

C

H COOCH3

CN

Cn

poly(methyl 2-cyanopropenoate)

Addition polymers

n

chloroethene

PVC

poly(chloroethene)

H

C C

Cl

HH

H

C

H H

Cl

Cn

Addition polymers

n

tetrafluoroethene

PTFE / Teflon

poly(tetrafluoroethene)

F

C C

F

FF

F

C

F F

F

Cn

Addition polymers

n

propene poly(propene)

H

C C

CH3

HH

H

C

H H

CH3

Cn

Addition polymers

• Catalysts are used for the polymerisation, and the exact mechanism depends on the catalyst and alkene (it is not electrophilic addition – it is usually catalytic addition).

• Polyalkenes are inert, although can burn.

• As they are inert, they are non-biodegradable.

Condensation polymers

• Condensation polymers are polymers formed from condensation reactions between monomers. A small molecule (often water) is produced as well as the polymer.

• Many natural polymers are condensation polymers, e.g. silk, starch and DNA.

• The two main types are polyesters and polyamides.

Polyesters

• Esters are formed on reaction between carboxylic acids and alcohols.

• Polyesters are formed when dicarboxylic acids react with diols.

• Polyesters are hydrolysed (in the presence of strong acid or a specific enzyme) into their constituent acid and alcohol, so they are bio-degradable .

Polyesters

HO C

O O

C OH OHHO HO OH

O

C OHHO C

O

strong acid or specific enzyme

- H2O

O

O

C OO C

O

C

O O

C O O

Polyesters

strong acid or specific enzyme

C

O

OHC

O

HO

benzene-1,4-dicarboxylic acid

HO CH2 CH2 OH

ethane-1,2-diol

n + n

terylene (PET)

C

O

O CH2 CH2 OC

O

n

+ 2n H2O

Polyesters

NH2H2N C

O

HO C

O

OHn n

benzene-1,4-diamine benzene-1,4-dicarboxylic acid

N C

O

C

O

N

HHn

+ 2n H2O

Kevlar

Polyesters

• Amides are formed on reaction between carboxylic acids and amines.

• Polyamides are formed when dicarboxylic acids react with diamines.

• Polyamides are hydrolysed (in the presence of strong acid or a specific enzyme), so they are bio-degradable.

.

.

Polyamides

strong acid or specific enzyme

HO C

O

(CH2)4 C

O

OH H2N (CH2)6 NH2n + n

hexanedioic acid 1,6-diaminohexane

nylon-6,6

C

O

(CH2)4 C N

O

H

(CH2)6 N

H n

+ 2n H2O

Polyamides

strong acid or specific enzyme

H2N (CH2)5 C

O

OHn

n

+ n H2O N (CH2)5 C

O

H