8. Polymers and Society Flashcards
What is a polymer?
A polymer is a molecule made up of thousands of units (monomers) strung together into very long chains
What is a monomer?
A monomer is a molecule that links together to form a polymer. They link together through a process called polymerisation.
What is polymerisation?
Polymerisation is the formation of giant molecules by repeated monomers that are joined by covalent bonds.
What is a Copolymer
A copolymer is a polymer formed from the polymerisation of two monomers.
What are the features of natural polymers?
- made of proteins of cellulose
- plants are made of cellulose and starch (protein) and consist of sugar monomers formed by condensation polymerisation
- animals are made of proteins that are also condensation polymers
What are the features of natural polymers?
- made of proteins of cellulose
- plants are made of cellulose and starch (protein) and consist of sugar monomers formed by condensation polymerisation
- animals are made of proteins that are also condensation polymers
What are the features of synthetic polymers
- made from raw materials obtained from fossil fuels or biomass (renewable organic matter that can be obtained from (recently) living plants or animals
- called plastics
What is addition polymerisation
The polymer is produced by a reaction between monomers that have a carbon-carbon double bond. Eg. molecules of ethene can react using a suitable catalyst to form the polymer polyethylene (common name) or polythene (IUPAC name)
It is the process in which monomers with at least one double carbon carbon bond react together to form a polymer by addition reactions.
The monomer must be an alkene. In the process of joining monomers together, one of these bonds is broken and the electrons are freed up and are used to form a new bond to the next monomer. This links the monomers together and forms the long chains.
An addition reacts is a reaction in which one molecule bonds covalently with another molecule without losing any other atoms; only one product is formed.
What is an amorphous polymer?
An amorphous polymer is a polymer that doesn’t have a crystalline structure; their atoms are held together loosely and their arrangement is not ordered nor predictable.
What is condensation polymerisation?
Condensation polymers form from monomers that have two functional groups per molecule. Such molecules are said to be difunctional. Polymerisation occurs when one functional group of one monomer reacts with one functional group on another. A small molecule (which is often water) is removed in the process. Because each monomer has one more functional group on it (they are difunctional), this process can be repeated on and on to produce longer polymer chains.
A condensation polymer is formed in a reaction in which two molecules combine to form a larger molecule, producing a small molecule such as HCl or H2O as a by-product. If the molecule lost is water, it can also be described as a dehydration reaction.
What are thermoplastic polymers?
Thermoplastic plastics may be repeatedly melted, reshaped and hardened by cooling. Eg. Polystyrene.
They soften on heating.
They are long chains that are tangled but not attached to each other, when heat is applied they can move past each other, they will get soft and if you apply pressure they will bend. They will stretch but not return to their original shape. They are easily recycled.
What are thermosetting polymers?
Thermosetting plastics do not melt but char when heated. They must be moulded or shaped during their manufacture. Eg. Bakelite.
Thermosetting polymers do not soften on heating and char if heated strongly.
They have lots of covalent bonds between the molecules. This makes them difficult to move (they are not stretchy) and don’t melt and are more difficult to recycle, they tend to be hard
What are linear polymers
Linear polymers are thermoplastic polymers, but they do not have side chains.
What are elastomers?
Elastomers are plastics that have a few cross links (covalent bonds between polymer molecules) Polymer molecules can move a bit, they will stretch out but will return to their shape when let go
