Conducting Polymers
- The covalent molecular structures of polymers make them excellent electrical insulators, which is why they are often used to protect people from electricity.
- We are now able to make polymers that can conduct electricity; however their uses have not been exploited yet. Conducting polymers will probably play a great role in the future of plastics.
How do they work?
- When ethyne molecules polymerise, the product formed is polyethyne.
- Polyethyne molecules contain alternating single and double bonds.
- There are two geometric isomers of polyethyne as the double bonds can be arranged in different orientations to each other.
- Like many of the other polymers, the conducting polymer was made accidentally, when a student of Shirakawa (who first discovered the red polyethyne after directing a steam of ethyne onto a surface of a Ziegler-Natta catalyst at a temperature of -78oC) used 1000 times too much catalyst.
- One year later, the polymer’s use was found when it was “doped” with iodine, producing a metallic golden sheet that conducted electricity one million times better than previous forms of polyethyne.
- The race is now on to develop these polymers so that they become even better polymers and to find commercial uses for them.
Alkynes
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Alkynes are like alkenes in that they form another class of the unsaturated hydrocarbon family.
- However, instead of the C=C double bond that characterise alkenes, the alkynes have a carbon carbon triple bond.
- Alkynes are named in a similar way to the alkenes, but using an “-yne” suffix rather than “-ene”.
Useful books for revision:
Revise AS Chemistry for Salters (Written by experienced examiners and teachers of Salter's chemistry)
Revise AS Chemistry for Salters (OCR) (Salters Advanced Chemistry)
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