Polymers

What Are Polymers?

•Large molecule that consists of lots of small repeating subunits•Subunits are called monomers•Polymers are formed when monomers are linked together is a process called polymerization

Addition Polymers

•Polymers are linked through addition reactions

•Three stages in synthesis• Initiation• Propagation• Termination

A A + A A + A A A A A A A A

A B A B A B A B A B A B + +

Polyethylene

•Polymer made from ethene monomers

Polyethylene

•Polymer made from ethene monomers

•Short form notation:

C C

H

H H

H

C C

H

H H

H

C C

H

H H

H

+ + C C C C C C

H

H

H

H

H

H

H

H

H

HH

H

nC CH

H

H

H

Polyethylene

Polypropene

•Made from propene monomers

Polypropene

•Made from propene monomers•Used in rope and carpets

•Short form notation:

C C C C C C

CH3

H

H

H

CH3

H

H

H

CH3

HH

H

C C

H

H CH3

H

C C

H

H CH3

H

C C

H

H CH3

H

++

C C

H

H CH3

H

n

Polyvinyl Chloride (PVC)

•Made with chloroethene (vinyl chloride) monomers

Polyvinyl Chloride (PVC)

•Made with chloroethene (vinyl chloride) monomers•Used in electrical wire insulation, plastic piping, coating on fabrics

•Short form notation:

C C C C C C

Cl

H

H

H

Cl

H

H

H

Cl

HH

H

C C

H

H Cl

H

C C

H

H Cl

H

C C

H

H Cl

H

++

C C

H

H Cl

H

n

Polystyrene

CH C

n

CH C

n

Polystyrene

•Made from (styrene) phenylethene •Very commonly used

Substituted Groups

•Change the properties of polymer

•Teflon monomer: tetrafluroethane

•Plexiglass monomer: methyl propenoate

Crosslinking•Occurs when links can be formed in 2 directions

• Diene monomers can form bridges between chains

•Diene doesn’t have to be main monomer•Increases polymers’ strength

Plastic Properties

•Substituted ethene (vinyl) monomers considered “plastics”•Saturated alkanes

• Very stable• Unreactive

•Flexible and mouldable solids or liquids

• Weak van der Waals forces•Softened by heating

• Disrupts forces

Condensation Polymers

•Monomer units are joined by condensation reactions•Monomer units must have functional groups at each end

Polyesters•Formed between dicarboxylic acid and diol

Polyesters•Formed between dicarboxylic acid and diol

OHCR

O

COH

O

+ O R O HH

CR

O

C

O

O R O

OH2+

nOH2

Polyamides

•Formed between dicarboxylic acid and diamine

Polyamides

•Formed between dicarboxylic acid and diamine

OHCR

O

COH

O

+ N R N HH

H

H

CR

O

C

O

N R N H

H

OH2+

n

OH2