12. Polymers Flashcards
Are polymers saturated?
Yes
What are monomers?
The constituent alkene molecules of polymers
What happens in addition polymerisation?
A large number of monomers are combined to form a single polymer chain, by firstly breaking the double bonds
What are polyalkenes?
Polymers made from alkene monomers
What are polymers?
When alkene molecules are joined to give large molecules
What property of polyalkenes makes them non-biodegradable?
They are chemically inert
How are polyalkenes disposed of?
By burning, burying in landfills or recycling
What is the difference between a drawing of the repeated unit and the polymer structure?
Repeating unit does not contain brackets or ‘n’
To form condensation polymers, what must monomers have?
A functional group on each end
What is it called when a monomer has a functional group on each end of the molecule?
Bifunctional
In monomers forming condensation polymers, do the functional groups have to be the same?
No - they can be the same or different
What is produced when a bond forms between two monomers in a condensation polymer?
A small molecule (e.g. H2O or HCl) depending on the monomers
What are the common types of condensation polymer?
- polyesters
- polyamides
- polypeptides
What holds condensation polymers together?
Intermolecular forces
What are the intermolecular forces between condensation polymers dependent on?
The atoms and bonds within the monomers
Why are condensation polymers biodegradable?
They can be hydrolysed - broken down into smaller fragments
Are condensation polymers biodegradable?
Yes
What is the main example of a condensation polymer where the monomers have different functional groups on either side?
Amino acid
What is formed when a carboxylic acid reacts with an alcohol?
An ester and water
What is formed when a dicarboxylic acid reacts with a diol?
A polyester and water
What is the use of terylene (PET)?
Making plastic bottles and clothing
What type of condensation polymer is PET?
Polyester
What is formed when a carboxylic acid reacts with an amine?
An amide and water
What is formed when a dicarboxylic acid reacts with a diamine?
A polyamide and water
What type of condensation polymer is kevlar?
Polyamide
Uses of kevlar?
- body armour → bulletproof vests and combat helmets
* manufacture gloves
What type of condensation polymer is nylon 6,6?
Polyamide
What small molecule is released in the production of nylon 6,6?
HCl
Uses of nylon?
- tights
- machine parts
- rope
How are polypeptides formed?
Many amino acids react and join together as water is released
Why will the repeating unit differ for different polypeptides?
Different amino acids are joined together in a specific sequence
When will a polypeptide with a common repeating unit be formed?
If a single amino acid is used
Why are amino acids polypeptides and polyamides?
They contain a carboxylic acid group and an amine group
What type of condensation polymer are amino acids classed as?
Polypeptides and polyamides
How are monomers identified from a section of the polymer chain?
Look for ester/amide linkage - this is where the monomers have joined together
Remember that atoms have been removed to join these together and there the functional groups need to be reformed
What is used to break down polypeptides?
Concentrated acid
What happens when amino acids are broken down with concentrated acid?
The amino acid monomers will be in the form of the protonated zwitterion
Why, when polypeptides are broken down, are amino acid monomers sometimes in the form of protonated zwitterions?
Concentrated acid is used to break down polypeptides
What is the strongest IMF between addition polymers that are non-polar?
Van der waal’s
When will the strongest type of IMF between addition polymers not be VDWs?
If they contain polar bonds, and are not hydrocarbons
Why do addition polymers have relatively high melting and boiling points?
Hydrocarbon chains are often very long, so many Van der Waal’s forces exist between the chains
Why do addition polymers tend to melt over a range of temperatures?
The chain length is variable, so there may be a different number of intermolecular forces between the chains
Why do addition polymers tend to be soft?
The chains are not rigidly held in place by each other
In condensation polymers, what is the strength of the IMFs between different chains in polyamides and proteins enhanced by?
Hydrogen bonding
What is the result of polyalkenes being chemically inert?
They have many uses, but are also not easily decomposed
Why are addition polymers chemically inert?
They are long saturated hydrocarbon chains
Which constitutes a smaller environmental hazard: addition or condensation polymers? Why is this?
Condensation polymers - polar carbon atoms that can be easily attacked by nucleophiles in hydrolysis
Why can condensation polymers undergo hydrolysis?
- they are made up of chains containing polar bonds
* polar C atoms can be readily attacked by nucleophiles and as a result the polymers can be broken up
Advantages of disposing of polymers through burning?
Prevents build up of polymers in the environment
Advantages of disposing of polymers through burying?
Prevents release of toxic/environmentally harmful gases
Advantages of disposing of polymers through recycling?
- helps preserve dwindling supplies of crude oil
* reduces amount of unrecycled plastic in landfill
Disadvantages of disposing of polymers through burning?
- form carbon particulates (C)
- form CO - toxic
- form H2O and CO2 - greenhouse gases
Disadvantages of disposing of polymers through burying?
- limited supply of landfill sites and lack of biodegradability means these will fill up
- leaching may mean that nearby groundwater supplies could become contaminated
Disadvantages of disposing of polymers through recycling?
Involves collection, sorting, melting and remoulding → all of which use energy and manpower → expensive
