Ring-Opening Metathesis Polymerization of Cycloolefens Using Tungsten-Tetraphenylporphyrinate Catalysts

Summary

Ring-opening metathesis polymerisation of cycloolefins (e.g. cyclopentene, cyclooctene, cyclododecene, dicyclopentadiene) has been investigated in the presence of recently reported catalytic systems consisting of tungsten-tetraphenylporphyrinate and aluminoxane, under inert atmosphere at room temperature, in aromatic solvents. The catalyst precursor was prepared by interaction of WCl₆ with free tetraphenylporphyrin in carbon tetrachloride and characterised by spectroscopic methods. Physical-chemical studies on the interaction between the catalytic components and with the monomer, as well as kinetic results indicated a high stability and efficiency of the catalytic system employed. It is of interest that the polyalkenamers displayed a high trans stereoconfiguration and a block or alternate distribution of the carbon-carbon double bonds dyads. These catalytic systems behaved as “living” ones and allowed polyalkenamers with monomodal and narrow molecular weight distribution to be produced. Block copolymers starting from dicyclopentadiene in conjunction with cyclopentene and cyclooctene have also been obtained. Data recorded under the above conditions gave information concerning the structure of the active species, the nature of the initiation and propagation steps, reaction mechanism and stereochemistry.