3.3.12 Polymers Flashcards
What are condensation polymers?
- Condesation polymers usually involve two different types of monomer, each with at least two functional groups. Each functional group reacts with a group on another monomer to form a link, creating polymer chains
- When a link is formed, a water molecule is lost - hense the name condensation polymerisation
Name three examples of condensation polymers
- Polyamides
- Polyesters
- Polypeptides (proteins)
Explain the reaction between dicarboxylic acids and diamines to make polyamides
The carboxyl group if dicarboxylic acids react with the amino group of diamines to form amide links. Dicarboxylic acids and diamines have a funtional group at each end of the molecule, so long chains can form
HOOC-R-COOH + H2N-R’-NH2 -> HOOC-RCONH-R’-NH2 + H2O
A water molecule is eliminated
CONH = amide link
Give the equation for the creation of Nylon 6,6
1,6-diaminohexane and hexandoic acid make Nylon 6,6
n H2N(CH2)6NH2 + n HOOC(CH2)4COOH -> -(-NH(CH2)6NHCO(CH2)4CO-)n- + 2nH2O
What uses does Nylon 6,6 have?
- Carpet
- Clothing
- Rope
- Airbags
- Parachutes
Give the equation for the creation of Kevlar
1,4-diaminobenzene + benzene-1,4-dicarboxylic acid -> Kevlar + H2O
n H2N(C6H4)NH2 + n HOOC(C6H4)COOH -> -(-NH(C6H4)HNCO(C6H4)CO-)n- + 2nH2O
Give the uses of Kevlar
- Bullet proof vests
- Boat construction
- Car tires
- Lightweight sports equipment
Explain how the reaction between dicarboxylic acids and diols to make polyesters
The carboxyl groups of dicarboxylic acids can react with the hydroxyl groups of diols to form ester links.
Polymers joined by esters are called polyesters.
HOOC-R-COOH + HO-R’-OH -> HOOC-R-COO-R’-OH + H2O
A water molecule is eliminated
Give the equation for the creation of Terylene (PET)
Benzene-1,4-dicarboxylic acid + ethane-1,2-diol -> Terylene (PET)
n HOOC(C6H4)COOH + n HOCH2CH2OH -> -(-OOC(C6H4)COOCH2CH2-)n- + 2nH2O
Give the uses of Terylene (PET)
- Plastic bottles
- Clothing
- Sheets
- Sails
By which process are condensation polymers broken down into their original polymers?
Hydrolysis - water molecules are added back to the polymer and the links are broken - e.g.
-(-CORCONHR’NH-)n- +2nH2O -> n HOOCRCOOH + n H2NR’NH2
How do you draw the monomers from a condesation polymer?
- Break the chain through the middle of the bond of the amide or ester link
- Add an OH or H to each end of the new molecule
- For a polyamide the monomers need to be a dicarboxylic acid and a diamine
- For a polyester the monomers need to be a dicarboxylic acid and a diol
Why are condensation polymers generally stronger and more rigid than addition polymers?
Condensation polymers are made up of chains containing polar bonds, e.g. C-N and C-O. So, aswell as VDW forces, there are permanant dipole-dipole forces and hydrogen bonds between the polymer chains.
Why are addition polymers useful but difficult to dispose of?
- Polyalkenes such as poly(ethene) and polystyrene are addition polymers. They are made up of non-polar carbon chains, which makes them unreactive and chemically inert
- This is advantageous whilst being used e.g. a polystyrene won’t react with coffee, however this does mean they are non-biodegradeable
Why are condensation polymers biodegradable, why is this still a problem?
Condensation polymers such as polyesters and polyamides do have polar bonds in thier chains, which makes them open to attack by nucleophile. This means they can be broken down by hydrolysis so these polymers are biodegradeable, however this is a very slow process