polymers Flashcards
what are the two types of polymerisarion
there are two types of polymerisation:
- addition
- condensation
what is addition polymerisation
an addition plymer forms when UNSATURATED MONOMERS react to form a polymer
the monomers contain C=C
chains dorm when same basic unit is repeated over and over
why are polyalkenes chemically inert
due to the strong C-C bonds and C-H bonds and the non-polar nature of the bonds
They are therefore non-biodegradable
what is condensation polymerisation
the two most common types of condensation polymers are polymers are polyamides which involve the formation of an ester linkage or an amide linkage
The monomers usually have the same functional group on both ends of the molecule e.g. di-amine, di carboxylic acid
what happens in condensation polymerisation
in condensation polymerisation there are two different monomers that add together and a small molecule is usually given off as a side product e.g. H2O HCL
what does the condensation reaction between carboxylic acid and alcohol form
carboxylic acid + alcohol - ester + water
if we have the same functional group on each end of molecule we can make polymers therefore
a polyester is formed
what does the condensation reaction between acyl chloride and alcohol
an ester + HCL
if we have the same functional group on each end of molecule we can make polymers therefore
a polyester is formed
what happens when a condensation reaction occurs between carboxylic acid and an amine
amide+ water
if we have the same functional group on each end of molecule we can make polymers therefore
a polyamide is formed
what happens when a condensation reaction occurs between acyl chloride and an amine
amide+ HCL
if we have the same functional group on each end of molecule we can make polymers therefore
a polyamide is formed
how can we make a polyamide/polyester from one monomer
it is possible for polyamides and polyesters to from one monomer, if that monomer contains both the functional groups needed to react
what is the chemical reactivity of condensation polymers
polyesters and polyamides can be broken down by hydrolysis and are, therefore, biodegradable
The reactivity can be explained by the presence of polar bonds which can attract species such as nucleophiles and acids
how can polyesters and polyamides be hydrolysed
polyesters and polyamides can be hydrolysed by acid and alkali
The hydrolysis will result in the original monomers forming - although the scientific acid or amine group will be in salt from depending on whether the conditions are alkaline or acidic
what are the intermolecular bonds between condensation polymer chains
polyesters have permanent dipole forces between the C=O groups in the different chains in addition to the vand der waal forces between the chains
polyamides (and proteins) have hydrogen boding between the oxygen in C=O groups and the H in the N-H groups in the different chains in additon to the van der walls forces
Polyamides will therefore have higher melting points than polyesters
how do we disposal polymers
via:
- Landfill
- Incineration
- Recycling
Landfill
The most common method of disposal of waste in UK
many are now reaching capacity
European regulations willmean councils are charges much more for using landfill
most polymers (polyalkenes) are non-biodegradable and take many years to break down
we could use more biodegrabable plastics, e.g. Polyamides and cellulose and starch based polymers to improve rates of decomposition
