Alicyclic polyimides derived from alkanone bis-spironorbornanetetracarboxylic dianhydrides

Abstract

Alicyclic tetracarboxylic dianhydrides having alkanone bis-spironorbornane structure were synthesized and polycondensated with aromatic diamines. The polyimide films were prepared by a thermal and a chemical imidization methods. Poly(amic acid)s possessed an inherent viscosity (ηinh) range of 1.1-0.5 dL/g and gave flexible films after cured at 300-350 °C under vacuum. All the polyimides possessed the 5%-wt loss temperatures in nitrogen in the range of 470-490 °C, and the glass transition temperatures over 290 °C. The high Tg may be due to a dipole-dipole interaction between the keto groups of the polymer chains as well as a development of rigid polyalicyclic units. The films had a coefficient of thermal expansion (CTE) range of 50-60 ppm/K. The polyimide films exhibited cutoffs at wavelengths shorter than 290 nm. Transparency in the visible region of each polyimide film was over 85%. The polymerization degree of PI(ChODA+3,4'-DDE) obtained by curing the reprecipitated poly(amic acid) at 300 °C for 1 h in vacuum was 17, whereas the value increased six times higher on heating at 350 °C for an additional 30 min. The result means that the post-polymerization took place over the Tg (335 °C). © 2013SPST.