Polymerisation of Cyclic Polyenes

Among cyclic polyenes, cyclic dienes, trienes and tetraenes have been ring-open polymerised via the metathesis reaction. Representative of the cyclodienes most commonly used for polymerisation are 1,5-cyclooctadiene, norbornadiene (bicyclo[2.2.1]hept-2,5-diene) and dicyclopentadiene as mono-, bi- and tricyclic diolefins respectively. Cycloocta-1,5-diene metathesis polymerisation is another approach to the preparation of 1,4-polybutadiene  

Nevertheless, such catalysts as WCU—SnMe4 allow, under specific conditions, norbornadiene polymerisation to linear, non-crosslinked polymers [140]. When the carbon atom at one double bond of norbornadiene is substituted, selective 

The metathesis polymerisation of dicyclopentadiene (endo, exo) yields a linear polymer when carried out with single-component homogeneous metathesis catalysts of the metallacyclobutane or metal alkylidene type in diluted toluene solutions [142, 143]. 

The polymer displays narrow molecular weight distributions characteristic of living polymerisation systems. Among catalysts exhibiting an ability to perform such controlled polymerisations of dicyclopentadiene according to scheme (40), titanacycles and Mo or W alkylidenes are representative [142, 143]  

If the heat is removed from the polymerisation system through dilution or by cooling the solution, a soluble linear polymer of dicyclopentadiene remains the final product [143]. 

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Polyacetylene has promise as a polymeric electroconducting material [26-31]. The simplest way to obtain this polymer is by polymerisation of acetylene, although alternative methods involving the metathesis polymerisation of cyclic polyenes are also effective. 

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