3.3.12 Polymers (A2) Flashcards
what is condensation?
small molecule eliminated (usually H2O) to form a larger molecule
how many monomers are condensation polymers usually formed from?
two
what properties do these monomers forming condensation polymers have?
each has two functional groups
name some examples of condensation polymers?
polyesters
polyamides
polypeptides
what is the linkage in a polyester?
ester linkage
what molecule is eliminated in formation of a polyester?
H2O
what are the two monomers which form a polyester (generic names and structures)?
diol and dicarboxylic acid or a molecule with both alcohol and a carboxylic acid functional group
which monomers is terylene made from?
benzene 1,4 dicarboxylic acid
ethane 1,2 diol
what is Terylene used for?
a fibre for making clothes
what is the linkage in a polyamide?
peptide linkage
which molecule is eliminated when a polyamide is formed?
H2O
what are the two monomers used to form a polyamide (generic names and structures)?
diamine and dicarboxylic acid
examples of polyamides?
Nylon, Kevlar
which monomers is Nylon-6,6 made from?
1,6-diaminohexane
hexanedioic acid
if you are making Nylon in the lab, what monomers would you use and why? what molecule is eliminated?
use hexane-1,6-diacyl chloride as the rate of reaction is much faster. HCl is eliminated
what is Kevlar used for?
In body armour (bullet proof vests, stab vests)
helmets
oven gloves
which monomers is Kevlar made from?
1,4 diaminobenzene
benzene 1,4 dicarboxylic acid
why is Kevlar so strong?
Rigid chains and close packing of flat aromatic rings
what are polypeptides?
what is the linkage?
peptide linkage
made from just one amino acid monomer
why are polyalkenes not biodegradeable?
non polar C-H and C-C bonds
why is it bad to burn polyalkenes?
releases CO2, CO, C (soot) and other toxic chemicals from monomers
where do most polyalkenes end up?
landfill sites
why can condensation polymers be broken down?
they have polar bonds
how can condensation polymers be broken down?
hydrolysis (opposite of condensation)
why does hydrolysis not happen in normal conditions?
very slow rate in standard conditions
what are the four stages needed when recycling polymers?
collected –> sorted –> melted –> reformed
what are the advantages of recycling polymers?
saves expense of crude oil and preserves a non-renewable resource
reduces landfill
disadvantages of recycling polymers?
energy and manpower is needed for collecting, sorting and melting the polymers, making it expensive
can only be done a limited number of times
what is the difference between addition and condensation polymerisation?
condensation makes the polymer and eliminates a small molecule; addition polymerisation breaks C=C to form only one product (just the polymer)
explain hydrogen bonding between polyamides
both C=O and N-H are polar bonds, as N’s electronegativity > H’s and O’s electronegativity > C’s
Hydrogen bonding between H+ and O- in different molecules
Uses the lone pair of electrons on the O atom
why do polyesters not show hydrogen bonding?
All O-H bonds are removed during polymerisation
