Spiro-Fluorene-Containing Cyclic Olefin Polymers
Saki Ishii, Yoshiya Ota, Shin‐ichi Matsuoka, Masato Suzuki
Abstract
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[5.2.1.0 2,6 ]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 ( T g ) 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 T g 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 ( C R ) 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.