Electronic conduction in polyacetylene

Indeed, such a polymer chain can be produced by the polymerisation of acetylene to yield a black, very hard solid. The rigidity of the polyacetylene comes 

The lifetime of the excited state wiU depend on the spin state and a bipolaron with the spins unpaired wiU have a longer Ufetime than that with spins paired. Studies of polyacetylene indicate that as the temperature is changed, so the dominant species changes. At higher temperatures conduction involves predominantly bipolaron states. 

The energy to promote the electrons to the lowest unoccupied molecular orbital can be provided by either photons, which is photoconductivity, or by phonons in the lattice, which is thermoconductivity. In the case of polyacetylene, the energy gap is sufficiently small for phonons to be able to promote electrons to the conduction state. 

Clearly, injection or removal of an electron from the conjugated backbone is essentially a chemical oxidation or reduction process. So polyacetylene is sensitive to oxidation by atmospheric oxygen. Oxygen can add to the polymer backbone and destroy the % conjugation, which in turn reduces the range of delocalisation of the electrons. This leads to a reduction in the conductivity of the polymer. 

In terms of polymer dynamics the chains are very rigid, but defects can arise because the backbone does not adopt a low entropy all-ifum structure. Part of the 

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