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Problems...

The synthetic procedure involved adding.
             Ti(OBu)4 and then Et3Al to a small volume of toluene under an inert atmosphere. The solution was allowed to.
             age at 20oC for 45 minutes and was then cooled to -78oC. The reaction vessel was evacuated and acetylene.
             gas introduced and allowed to react with a film of the catalyst which had already formed on the walls of the.
             reaction vessel. A film of polyacetylene immediately formed there2. The reaction was controlled by.
             evacuating unreacted acetylene gas. This procedure produced a copper-coloured film of all-cis-polyacetylene.
             with a cis content of some 95 %. Shirakawa's procedure also allowed silvery all-trans-polyacetylene to be.
             formed by running the reaction in n-hexadecane at 150oC. However, its conductivity was relatively modest:.
             cis-polyacetylene 10-8.
             -10-7.
             S m-1 and trans-polyacetylene 10-3.
             -10-2.
             S m-1.
             FIGURE 4.
             All-cis- and all-trans-polyacetylene.
             In 1975 Professors Alan Heeger and Alan MacDiarmid collaborated to study the metallic properties of a.
             covalent inorganic polymer, (SN)x . They shifted their attention to polyacetylene after MacDiarmid had met.
             5.
             Shirakawa in Tokyo. During a visit at the University of Pennsylvania, Shirakawa refined the polymerisation.
             of polyacetylene. With his experience from the (SN)x materials, MacDiarmid wanted to modify the.
             polyacetylene by iodine treatment. Shirakawa and Ikeda had previously noted that treating silvery.
             polyacetylene films with bromine or chlorine decreased the infrared transmission without altering the colour.
             MacDiarmid now turned to Heeger in whose laboratory a conductivity of 3000 S m-1 was measured for.
             iodine-modified trans-polyacetylene, an increase of seven orders of magnitude over the undoped material.
             The seminal paper received for publication on May 16, 1977, had the title: Synthesis of electrically.
             conducting organic polymers: Halogen derivatives of polyacetylene (CH)x. 1 Two other papers received later.
             in the same year elaborated further on the topic.


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