An American called MacDiarmid took
an interest in this, not because of the temperature
dependent mixes but because very few polymers had a metallic colouring, and his work was
largely dependent on similar looking inorganic polymers.
9The Discovery of Conducting Polymers |
In 1958 Natta et all made poly(acetylene) which is a conjugated polymer that is a semi-conductor. Ten years later an accident in an experiment started a new interest into conducting polymers.5 |
The black powder that Natta and his work force made, conducts electricity in the region between 7 × 10-11 and 7 × 10-3 Sm-1
In 1967 a Japanese postgraduate of Hideki Shirakawa added 1000 times too much Ziegla Natta catalyst 8 which resulted in a metalic looking film which was as good at conducting electricity as the best of the black powders. This silvery new film was trans-polyacetylene. Shirakawa investigated it and found that by repeating the experiment at a different temperature he could produce the coppery coloured cis form of the polymer. By adjusting the conditions of reaction different ratio mixes of the polymers could be made and so at a conference in Tokyo he introduced his discovery.
An American called MacDiarmid took
an interest in this, not because of the temperature
dependent mixes but because very few polymers had a metallic colouring, and his work was
largely dependent on similar looking inorganic polymers.
9
MacDiarmid and his co-worker Heeger were investigating the optical properties of metallic looking polymers and had found out that physical changes occurred by oxidising the substance. On inviting Shirakawa to their laboratories in Philadelphia they began investigating the different isomers of the polyacetylene by oxidising the polymer with iodine vapour. When some of Heeger's students were analysing the results they found that the conductivity had increased to 10 × 104 Sm-1 over ten million times.
In the summer of 1977 the three of them published an article called Synthesis of electrically conducting organic polymers: Halogen derivatives of polyacetylene; in The Journal of Chemical Society, Chemical Communications. The three scientists subsequently won the Nobel Prize for Chemistry in 2000.
In 19805, this branch of polymer studies had resulted in the synthesis of polyheterocycles, which are more air stable. Also the sidegroups of the monomers were being investigated so as to produce polymers with different conductive properties.
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| Laura White: 24/05/04 |