Synthesis and characterization of novel polyimide-based NLO materials from poly(hydroxy-imide)s containing alicyclic units (II)

A series of polyimide-based second-order nonlinear optical (NLO) materials were synthesized from poly(hydroxy-imide)s containing alicyclic units, followed by the Mitsunobu reaction with NLO chromophores. The resulting polymers were highly soluble in aprotic polar solvents such as DMF, DMAc, NMP, etc. The NLO polyimides exhibited the inherent viscosity range of 0.22-0.50 dL/g. Molecular structural characterization for the resulting polymers was achieved by H-1-NMR, FT-IR, and UV-visible spectroscopies. The glass transition temperature for the resulting NLO polyimides was in the range of 161 degrees C-233 degrees C and most of them showed high thermal stability. The polymer solutions could be spin coated on the indium-tin-oxide (ITO) glass or quartz disc substrates to form the optical quality thin films. The electro-optic coefficients (r(33)) at the wavelength of 1.3 mu m for polymer thin films poled around the glass transition temperature were in the range of 2-6 pm/V. And, long-term thermal stability of the dipole alignment was observed up to ca. 140 degrees C. (C) 1999 Elsevier Science Ltd. All rights reserved.