Polyacetylene via Ziegler-Natta

ds-trans isomerization is believed to occur during doping. The single bonds in 

The baniv for conversion firom dsoid to transoid is much lower than for ds/trans isomerization in which the pi (second) bond must formally be broken and reformed. 

All four combinations of ds/trans single/double bonds in planar as well as nonplanar structures have been considered and a variety of conformations induding helical structures have been proposed. Also, neilher ds- nor trans-polyacetylmre contains double bonds of exdusively one type. It has been acknowledged that, evoi after isomerization, residual ds units exist in tnms-polyacetyiene.  

Figme 27. Polymerization of acetylene showing ds and trans isomers. 

A number of block and graft copolymers of polyacetylene have been synthesized, generally with the idea of using the second half of the block as a solubilizing tail. In most cases, this modification rendmed the polymer soluble and has allowed a variety of studies of the 235 nor near2 . optical properties as weU as 

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