Synthesis, thermal and gas permeation properties of new silicon containing ROMP polytricyclodecadienes

New bis-trimethylsilyl-substituted poly(tricyclo[4.2.2.02,5]deca-3,9-diene) (PTDDSi2) and poly(tricyclo[4.2.2.02,5]deca-3,7,9-triene) (PTDTSi2) were synthesized by ring-opening metathesis polymerization of the corresponding new monomers in the presence of 1st ‒ 3d generation Grubbs’ catalysts. For monomer synthesis, the reaction of chlorosilanes with 1,3,5,7-cyclooctatetraene was studied for the first time. Polymerization conditions (catalyst type, temperature, monomer concentration) were selected to provide 77–96% yield of polymers. The monomer and polymer spatial structure had a significant effect both on their synthesis and on properties. The high Тg of PTDDSi2 (above the Td), as well as the easily proceeding retrodiene decomposition of the PTDTSi2 with the formation of bis(trimethylsilyl)benzene and polyacetylene (at 98 °C) indicated high rigidity of the polymer chain. A gas permeability investigations of mono-(PTDDSi), bis-Me3Si-substituted PTDDSi2 and hydrogenated product H-PTDDSi2 showed that PTDDs belong to the group of polymers with moderate gas permeability (PO2 up to 100 Barrer). Nonetheless, PTDDSi2 exhibited “solubility controlled permeability”, which is unusual for moderately permeable polymers.