Practise condensation-polymer structures, polymerisation classification and structure-based degradability, deducing repeat units and monomers from diols, dicarboxylic acids and…
Lactic acid, CH3CH(OH)COOH, is the only monomer needed to form the polymer polylactic acid, PLA.
Draw a short length of the PLA polymer chain, including a minimum of two monomer residues. The methyl groups may be written as −CH3 but all other bonds should be shown fully displayed.
Label one repeat unit of polylactic acid on your diagram.
diagram has trailing bonds, two or more monomer residues AND either repeat unit correct OR ester linkage correct [1]
diagram fully correct [1]
Give the name of the type of polymerisation involved in the formation of PLA and the name of the functional group that forms between the monomers.
type of polymerisation
functional group
condensation AND ester [1]
Predict whether PLA is readily biodegradable. Explain your answer.
it is biodegradable because it can hydrolyse [1]
Copper is a transition element and has atomic number 29.
Under certain conditions, ethane-1,2-diamine reacts with ethanedioic acid, HO2CCO2H, to form the polymer Z.
Draw the structure of this polymer, Z, showing two repeat units.
amide bond, displayed or –CONH–
rest of the molecule with continuation bonds
O
O
H
N
N
H
O
H
N
O
N
H
1
1
Name the type of reaction occurring during this polymerisation.
condensation / addition – elimination 1
Polymer Z is an example of a biodegradable polymer.
Name a polymer that is non-biodegradable.
any named polyalkene / eg polyethene, PVC
allow Bakelite or Kevlar
1
1
Total: 20
1,3-diaminopropane, H2NCH2CH2CH2NH2, can be used to make polyamides.
Identify one compound that would react with 1,3-diaminopropane to form a polyamide.
either a dioic acid or a dioyl chloride [1]
Draw a section of the polymer chain formed from 1,3-diaminopropane and the compound you chose in (e)(i).
Your answer should:
- include four monomer residues (two of each type of monomer)
- show the amide link fully displayed
- clearly identify one repeat unit of this polymer.
trailing bonds
- two of each monomer residue, consistent with ei [1]
- repeat unit identified
- amide link showing C=O[1]