The ring-opening metathesis polymerization (ROMP) of cyclic oligomers of butadiene (c,c-l,5-cyclooctadiene -COD -, f,t,f-l,5,9-cyclododecatriene -CDT -), the acyclic diene metathesis (ADMET) of 1,5-hexadiene and the intramolecular metathesis degradation of 1,4-polybutadiene (1,4-BR) were studied using stable tungsten and molybdenum carbene complexes as well as conventional metathesis catalysts. The determination of cyclic oligomers up to rings containing eight butadiene units shows, compared to the literature, different results regarding the distribution, concentration and cishrans ratio. Kinetic studies of the ROMP of COD and the intramolecular metathesis of 1,4-BR allow to explain the discrepancy. The ROMP product spectrum for the cyclobutene system known and accepted until now in the literature as ring-chain equilibrium is controlled kinetically and far apart from thermodynamic equilibrium according to our results.

Copolymers of 1,5-cyclooctadiene (COD) and [2.2]paracyclophane-1,9-diene (PCPDE) were prepared by metathesis reaction using a well-defined tungsten carbene complex as catalyst. UV/Vis and 'H NMR spectroscopy give evidence for a dissection of the opened PCPDE molecule into separate p-phenylenevinylene units in the course of the polymerization. These units are distributed randomly in the polymer chain. This was confirmed by the metathetical preparation and spectroscopic investigation of a model substance and the comparison with spectra of compounds similar to the p-phenylenevinylene units in the copolymer.

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