MC test: Condensation polymers

Multiple choice test on A.9 Condensation polymers

Use the following 'quiz' to test your knowledge and understanding of this sub-topic. As this relates to a sub-topic on the options you may need access to the IB data booklet.

If you get an answer wrong, read through the explanation carefully to learn from your mistakes.

Which two monomers undergo a polycondensation reaction with the lowest atom economy?

Since hydrogen chloride has a greater molar molecular mass than water, the atom economy will be lower when a diacyl chloride is used as one of the monomers compared to using a dioic acid. The atom economy will be lower when the product is nylon 6,6 compared to nylon 6,10 as the ratio of the mass of polyamide formed compared to the mass of the inorganic product formed will be lower.

 

Which can react together to form a polymer that contains peptide bonds?

I. hexane-1,6-dioic acid, HO−CO−(CH2)4−CO−OH and ethane-1,2-diol, HO−(CH2)2−OH

II.  alanine, H2N−CH(CH3)−COOH and serine, H2N−CH(CH2OH)−COOH

III. hexanedioyl dichloride, Cl−CO−(CH2)4−CO−Cl and 1,6-diaminohexane, H2N−(CH2)6−NH2

When a monomer containing an amine group, −NH2 reacts with either a monomer containing an acyl chloride, −COCl or a monomer containing a carboxyl group, −COOH the resulting condensation product will contain a peptide bond, −CO−NH−. 

 

Which reaction can produce a polyester?

To form a condensation polymer both monomers must contain at least two reactive functional groups. Diacyl chlorides and diols or dicarboxylic acids and diols react to form polyesters whereas dicarboxylic acids and diamines react to form polyamides.

 

How many molecules of water will be produced when 1000 molecules of hexane-1,6-dioic acid react completely with exactly 1000 molecules of 1,6-diaminohexane to form nylon 6,6?

Because each of the monomers contains two reactive groups, two molecules of water will be produced for every one molecule of the dioic acid that reacts with a molecule of the diol. One end of the polymer chain will contain an unreacted hydrogen atom and the other end an unreacted hydroxyl group, -OH, so the number of water molecules produced is (2 x 1000) minus one.

 

Which is the repeating unit of nylon 6,6?

The repeating unit must be able to bond to other repeating units so has no has no −OH or −H on the end. Nylon 6,6 is made from monomers that each contain six carbon atoms.

 

Why does Kevlar break down in concentrated sulfuric acid solution?

Kevlar owes its strength to the cross linking formed between chains by hydrogen bonding. Sulfuric acid prevents this by protonating the O and N atoms so they can no longer be involved in forming hydrogen bonds across the chains. Sulfuric acid will also break down the carboxamide (peptide) bonds in the chains themselves.

 

Kevlar has the structure:

Which two compounds could be used to make Kevlar?

Kevlar is made from 1,4-diaminobenzene and benzene-1,4-dicarbonyl chloride.

 

Under certain conditions acidic solutions of Kevlar show lyotropic liquid crystal behaviour. Which factors affect the ability of Kevlar to show this behaviour?

I. concentration

II. temperature

III. pH

The definition of lyotropic is that it depends upon the concentration of the Kevlar in solution. It also depends upon the temperature and the pH of the acid solution (i.e. the acid concentration). If the pH is too low, i.e. the acid is concentrated, the amide linkages in the chains of Kevlar can be decomposed.

 

What type of forces of attraction are responsible for bonding the chains of Kevlar together causing a very ordered and strong three dimensional cross-linked lattice?

The H on the -NH- of the amides in one chain hydrogen bond to the O on the -CO- of the amides in an adjacent chain.

 

Which can be made either entirely or partially from Kevlar?

I. Bulletproof vests

II. Composites

III. Optical fibre cables

Kevlar has been used to make lightweight bulletproof vests since 1976. Kevlar is a key component of Aramid fibre composites and can be used to make the sheath around optical fibre cables to prevent the cable from damage or kinking. 

 

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