20. Polymerisation
A section of Chemistry, 9701
Listing 10 of 116 questions
The physical properties of polymers depend on the average relative molecular mass of the polymer chains and on the functional groups present in the monomers. The presence of side-chains in addition polymers can increase the spacing between polymer chains in the bulk substance and hence reduce the overall density. In condensation polymers it is the nature of the side-chain that is often more important since this can lead to cross-linking of the polymer chains forming a three-dimensional structure. For each of the following polymers, give the structure of the monomerand state the type of reaction used to produce the polymer. N H polymer A (CH2)6 (CH2)4 N H C O C O n monomertype of reaction polymer B H C H C CH3 H C H H C CH3 H n monomertype of reaction N H polymer C (CH2)5 C O n monomertype of reaction Look at the structures of the three polymers and answer the following questions. Suggest why the density of B is lower than that of A. Which polymer will have the weakest forces between chains, and what is the nature of these forces?
9701_w12_qp_43
THEORY
2012
Paper 4, Variant 3
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Super-absorbent polymers have the ability to absorb 200-300 times their own mass of water. They are classifi ed as hydrogels and they are widely used in personal disposable hygiene products such as babies’ nappies . These polymers are commonly made by the polymerisation of compound K mixed with sodium hydroxide in the presence of an initiator. CH2 C H CO2H K Explain what is meant by the term polymerisation. What type of polymerisation is involved in the formation of hydrogels? Describe the changes in chemical bonding that occur during the polymerisation of K. Acrylic acid is the common name for compound K. Suggest the systematic name of K. Draw the structure of at least two repeat units of the polymer formed by the above method from acrylic acid, K, when mixed with NaOH. The C–C–C bond angle in compound K changes when the polymer is formed. State and explain how the C–C–C bond angle differs between a molecule of K and the polymer. angle changes from to explanation Draw a detailed diagram of a portion of the polymer you have drawn in to explain how it can absorb a large volume of water. A student added 0.10 g of the polymer to 10 cm3 of aqueous copper(sulfate solution. Predict, with a reason, what you expect to observe. Compound L, CH2=CHCONH2, can also be polymerised to form a super-absorbent polymer. Name the two functional groups in compound L. Compound K can be converted into compound L by the following two-step route. H2C CO2H H C H2C CO2 –NH4 + H C K H2C CONH2 H C L step 1 step 2 Suggest a reagent for step 1. What other product is formed in step 2? State the reagents and conditions necessary to re-form K from L.
9701_w13_qp_41
THEORY
2013
Paper 4, Variant 1
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Super-absorbent polymers have the ability to absorb 200-300 times their own mass of water. They are classifi ed as hydrogels and they are widely used in personal disposable hygiene products such as babies’ nappies . These polymers are commonly made by the polymerisation of compound K mixed with sodium hydroxide in the presence of an initiator. CH2 C H CO2H K Explain what is meant by the term polymerisation. What type of polymerisation is involved in the formation of hydrogels? Describe the changes in chemical bonding that occur during the polymerisation of K. Acrylic acid is the common name for compound K. Suggest the systematic name of K. Draw the structure of at least two repeat units of the polymer formed by the above method from acrylic acid, K, when mixed with NaOH. The C–C–C bond angle in compound K changes when the polymer is formed. State and explain how the C–C–C bond angle differs between a molecule of K and the polymer. angle changes from to explanation Draw a detailed diagram of a portion of the polymer you have drawn in to explain how it can absorb a large volume of water. A student added 0.10 g of the polymer to 10 cm3 of aqueous copper(sulfate solution. Predict, with a reason, what you expect to observe. Compound L, CH2=CHCONH2, can also be polymerised to form a super-absorbent polymer. Name the two functional groups in compound L. Compound K can be converted into compound L by the following two-step route. H2C CO2H H C H2C CO2 –NH4 + H C K H2C CONH2 H C L step 1 step 2 Suggest a reagent for step 1. What other product is formed in step 2? State the reagents and conditions necessary to re-form K from L.
9701_w13_qp_42
THEORY
2013
Paper 4, Variant 2
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Polymers can be formed by addition or condensation polymerisation. Complete the table. polymer method of polymerisation nylon PVC Terylene Nomex is a polymeric material with excellent fl ame-resistant properties. It contains a polymer made from the two monomers shown below. NH2 H2N CO2H HO2C Draw the structure of the polymer showing two repeat units. The linkages between monomer units should be shown fully displayed. Proteins are natural polymers. Explain what is meant by the primary structure of a protein. Use the diagram to show an example of how the α-helix secondary structure in proteins is stabilised. The tertiary structure of a protein is destroyed during the process of denaturation. Explain how this can occur by the addition of alkali, the addition of Hg2+ ions, heating to 70 °C.
9701_w14_qp_43
THEORY
2014
Paper 4, Variant 3
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Questions Discovered
116