Spiro-Fluorene-Containing Cyclic Olefin Polymers

For application to optical polymer materials with a high refractive index and low birefringence as well as high thermal stability and low hygroscopicity, we have performed the ring-opening metathesis (co)polymerization (ROMP, ROMCP) of fluorene-based norbornene (NB) monomers, spiro[fluorene-9,4′-tricyclo[5.2.1.02,6]dec-8-en] (endo-1 and exo-1) and subsequent hydrogenation to produce spiro-fluorene-containing cyclic olefin polymers. The living ROMP and the kinetics of the ROMCP with NB were investigated. A series of hydrogenated endo- and exo-isomeric polymers, H-poly(1) and H-poly(1-co-NB), with random, gradient, and block sequences, were synthesized and characterized. They are highly soluble in common organic solvents due to their large fractional free volume, as indicated by broad X-ray diffraction patterns. The glass-transition temperatures (Tg) of H-poly(1-co-NB) significantly increased with the content of 1 up to 273 °C [H-poly(endo-1)]. The endo-isomeric polymers exhibited significantly higher Tg values and slightly lower solubility than their exo-counterparts, probably because of the slightly smaller fractional free volume of the endo-isomers. The refractive indexes of H-poly(1)s are as high as 1.61, and the stress-optical coefficients in the rubbery state (CR) of H-poly(1-co-NB) are less than zero. These low birefringences and large fractional free volumes are derived from the bulky spiro-fluorene moiety oriented vertically to the polymer main chain.