Polymerisation of Monoalkynes

Interesting features in the polymerisation of acetylenic monomers are displayed by rhodium-based catalysts they may be applied in metal akyl or hydride-activated systems, e.g. RhCl3-LiBH4 [49] and [(Cod)Rh]1 [[BPh4] 

An original method for acetylene polymerisation is that using bis(ylide)nick-el(II) catalysts with a highly active Ni-Ph bond [74,75]  

The cis-trans content of polyacetylene formed with coordination catalysts depends on the polymerisation temperature the increasing trans content with increasing polymerisation temperature has been explained in terms of a thermally induced cis-trans isomerisation which occurs before crystallisation of the chain segment [10,76 78], 

In an alkyne polymerisation system with Ziegler-Natta catalysts, chain transfer and termination reactions, similar to those postulated for olefin polymerisation, have been suggested to take place [25]. A possible chain transfer reaction is the formation of the Ti H species from the propagating chain end by /h hydride elimination  

It is worth noting that suitable olefins added to the polymerisation system can act as chain transfer agents during the metathesis polymerisation of acetylenic monomers for instance, trimethylvinylsilane has been found [84] to be an effective chain transfer agent in the polymerisation of phenylacetylene in the presence of the WC16—SnPh4 catalyst. 

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