Polymer Revolution

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  • Created by: polly
  • Created on: 27-04-13 15:37
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Have one or more C=C bonds ­ said to be unsaturated ­ all bond angles around double bond are 120o as there is 3 sets of electron density around each carbon
General formula is CnH2n
-A-A-A-A- polymers made from one type of alkene monomer
-B-B-B-B- polymers can be made from more than one alkene monomer
Electrophilic addition: where an electrophile is attracted to the negatively charged C=C region in an alkene and accepts a pair of electrons from the double bond.
Electrophile: positive ions or molecules with a partial positive charge.
Mechanism for adding Bromine to ethene - PREECA
- Polarisation: bromine molecule approaches an alkene and becomes polarised.
- Repulsion: the electrons in the molecule are repelled back due to the high electron density in the alkene C=C bond.
- Electron density: the electrons are unevenly distributed, making the bromine atom closest to the alkene slightly positively charged.
- Electrophile: the bromine atom now acts as an electrophile, accepting a pair of electrons from the alkene and forming a C-Br bond.
- Carbocation: the carbon species is now positively charged, becoming a carbocation.
- Another bond: the other bromine atom, now negatively charged, moves in and forms another bond with the carbon chain.
Electrophile Product Conditions
Br2 CH2BrCH2Br Room temp
1,2-dibromoetha and pressure
Br2 (aq) CH2BrCH2OH Room temp
2-bromoethanol and pressure
HBr (aq) CH3CH2Br Aqueous
Bromoethane solution,
room temp
and pressure
H2O CH3CH2OH Conc. H2SO4
Ethanol then H2O at
H2 CH3CH3 Pt catalyst,
Ethane room temp
and pressure

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Structure and properties of polymers
Factors affecting properties of polymers - BSSCCC (think of a biscuit)
- Branching: if the polymer is straight and unbranched, the chains pack more closely giving stronger bonds, therefore a stronger polymer.
- Stereoregularity: the more regular the orientation of the side groups, the closer the packing, thus the stronger the molecule.
- Side groups: more polar side groups leads to stronger bonds between chains, thus a stronger polymer.…read more

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Large dipole between small hydrogen atom and a highly electronegative atom.
Small H atom is able to approach close to other atoms to form hydrogen bond.
There needs to be a lone pair of electrons on an O, F or N atom for which the hydrogen can line up with.
In hydrogen fluoride there are hydrogen bonds between the molecules.
Each hydrogen atom acquires a partially positive charge because it is bonded to a highly electronegative fluorine atom.…read more

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TERTAIRY doesn't oxidise
Dehydration of alcohols (elimination reaction)
Lose a molecule of water to produce an alkene
Reaction conditions: Al2O3 catalyst at 300oC at 1atm OR refluxing with conc. sulphuric acid
Infrared spectroscopy
The fingerprint region is below 1500cm-1
Why do molecules absorb IR radiation?
Each bond has its own frequency of vibration, which depends on what type of bond it is
When exposed to IR radiation each bond absorbs energy at a particular frequency.
This causes it vibrate more vigorously.…read more


john k

Thanks for this, it's a great resource. 


This is amazing, thank you :)


really good thanks :)

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