Addition Polymerisation (Cambridge (CIE) AS Chemistry)

Addition polymers are made by the polymerisation of alkenes.

Explain what is meant by the term addition polymerisation.

Trans-hept-2-ene can be made into an addition polymer.

i) Give the displayed formula of trans-hept-2-ene.

[1]

ii) Draw the structure of poly(hept-2-ene) showing two repeat units.

[1]

Suggest why the polymer made from trans-hept-2-ene is not called poly(trans-hept-2-ene).

Trans-hept-2-ene is a liquid at room temperature and pressure but poly(hept-2-ene) is a solid.

Explain why there is a difference in the states of trans-hept-2-ene and poly(hept-2-ene).

Polyvinyl chloride (PVC) is a polymer which is rigid enough for use as a drainpipe and flexible enough for plastic aprons.

State the IUPAC name of PVC.

Fig 2.1 below shows a section of the PVC polymer.

Fig 2.1

i) Draw the repeating unit of PVC.

[1]

ii) Draw the structure and state the name of the monomer of the PVC polymer.

[2]

iii) Write the equation to represent the formation of PVC from its monomer.

[1]

The polymer poly(propene) is formed from the monomer propene.

i) Draw the repeating unit of this polymer.

[1]

ii) The properties of two different polymers, poly(methylpropene) and poly(ethene) are compared to each other. Complete Table 2.1 by placing an X in the correct box. You may place more than one X for each physical property. 

[3]

Table 2.1

iii) Explain why the melting point of poly(methylpropene) is much higher than that of methylpropene. 

[2]

Polymers are unreactive compounds due to their long non-polar chain of saturated carbon-carbon and carbon-hydrogen bonds. Though this means that they are safe to use due it also means that they are non-biodegradable as they are not attacked by biological agents such as enzymes. 

Table 2.2 shows three different ways in which polymers can be disposed of.

Table 2.2

State the disadvantage of each method of disposal to complete Table 2.2.

This question is about different polymers and their uses.

Poly(tetrafluoroethene), also known as PTFE, is an addition polymer used as a non-stick coating in pans as it is very unreactive.

Draw the displayed formula of the monomer used to form PTFE.

Draw two repeating units of poly(tetrafluorethene).

The table shows the melting points of two polymers.

Explain the differences in melting point of these two polymers in terms of the intermolecular forces between the chains.

Poly(ethene) bags pollute the environment for a long time because they are non-biodegradable.

Describe two pollution problems that are caused by non-biodegradable polymers.

The structures of two different polymers, poly(ethene) and poly(propene) are shown in Fig. 4.1.

Fig. 4.1

Suggest two reasons why these polymers are unreactive.

State one advantage and one disadvantage of the unreactivity of addition polymers.

Another example of a polymer is polystyrene which is often used as packing material and electrical insulation.

Fig. 4.2 shows three repeating units of the polymer.

Fig. 4.2

Draw the structure of monomer X which is used to form the polymer shown in Fig. 4.2.

Two different monomers can also join together to form an addition polymer.

Monomer X can react with monomer Y to form a polymer. Two repeating units of this polymer are shown in Fig 4.3.

Fig. 4.3

i) Draw the structures of monomer Y which reacts with monomer X to form the polymer shown in Fig. 4.3.

[1]

ii) State the IUPAC name of monomer Y.

[1]

Poly(but-1-ene) is insoluble in water so is used in applications such as making water pipes

Write an equation to show how poly(but-1-ene) is formed from the monomer but-1-ene.

Not all polymers are insoluble in water. One example is poly(vinylalcohol) known as PVA. PVA is used in applications such as in the casing of detergent-filled capsules.

A section of the polymer chain of PVA is shown in Fig. 5.1.

Fig. 5.1

i) Draw the structure and give the IUPAC name of the monomer of PVA.

[2]

ii) Suggest why PVA is soluble, but poly(but-1-ene) is not.

[2]

Combustion can be used to dispose of poly(alkenes), such as poly(but-1-ene).

Give one advantage and one disadvantage to the environment of disposing of polymers by combustion.

Poly(chloroethene), PVC, can also be disposed of via combustion but it produces toxic waste gases including hydrogen chloride.

Suggest a reagent that can be used to remove this toxic gas from the waste gases.

Poly(methyl methacrylate) is used as a glass substitute in Perspex. 

A section of the polymer chain is shown in Fig. 1.1. 

Fig. 1.1

Draw the skeletal formula of the monomer. 

Explain why poly(methylmethacrylate) is fairly unreactive. 

Bioplastics, such as biodegradable plastics offer a sustainable alternative to oil-based products.

Where the use of plant-based polymers is not possible, photodegradable polymers are being developed. 

i) Explain how photodegradable polymers are broken down. 

[1]

ii) Suggest two disadvantages of using photodegradable polymers.

[2]

Explain how p-orbitals are involved in the formation of the C=C bond in chloroalkenes.

You should include a sketch in your answer. 

Compound Y has six possible structural isomers of C₃H₃Cl₃. 

Two of these isomers are shown in Fig. 2.1.

Fig. 2.1

i) State the IUPAC name of isomer 1.

[1]

ii) Draw three other structural isomers of C₃H₃Cl₃ that are chloroalkenes. 

[3]

iii) Show two repeat units for the polymer formed by isomer 2. 

[1]

Polymers can be disposed of by incineration. 

i) Write a balanced symbol equation for the incineration of poly(chloroethene).  Carbon dioxide, water and HCl are formed.

[1]

ii) Describe the environmental impact of this reaction and explain how it could be reduced. 

[3]

But-2-ene, CH₃CH=CHCH₃, is an important compound which is obtained from the cracking of hydrocarbons present in crude oil.

Some reactions of but-2-ene are shown in Fig. 3.1.

Fig. 3.1

Give the structural formulae of the organic compounds A to C.

But-2-ene can be polymerised to give poly(butene). Draw the structural formula of a portion of the polymer chain in poly(butene) showing two repeat units.

Explain why there is an increasing demand for polymers to be recycled rather than incinerated.