Solvent‐Free Ring‐Opening Metathesis Polymerization of Norbornene over Silica‐Supported Tungsten–Oxo Perhydrocarbyl Catalysts

Ring opening metathesis polymerization (ROMP) of bicyclo[2.2.1]hept‐2‐ene (norbornene) is carried out over silica‐supported catalysts based on tungsten complexes bearing an oxo ligand ( 1 : [(SiO)W(O)(CH 2 SiMe 3 ) 3 , 2 : [(SiO)W(O)(CHCMe 2 Ph)(dAdPO)], dAdPO 2,6 diadamantyl‐4‐methylphenoxide, 3 : [(SiO) 2 W(O)(CH 2 SiMe 3 ) 2 ]). The evaluation of the catalytic activities of the aforementioned materials in ROMP indicates that at low reaction time (0.5 min), the highest polymer yield is obtained with catalyst 2 . However, for longer reaction time (>2 min), complex 3 , a model of the industrial catalyst, exhibits a better monomer conversion. The polymers obtained are characterized. Moreover, these catalysts are shown to be rather preferentially selective to give the cis polynorbornene (>65%), characterized by high melting points (≈300 °C). The experimental values of the average molecular weight (M n ) of polynorbornenes are found to be close to the theoretical ones for the polymers prepared using catalyst 2 and higher for those originated from catalyst 3 .