ABSTRACT
2,3-Bis-(3,4-dicarboxyphenylcarboxyethoxy)-4′-nitrostilbene dianhydride ( 4 ) was prepared and reacted with 4,4′-oxydianiline and 4,4′-diaminobenzanilide to yield unprecedented novel polyimides 5–6 containing 2,3-dioxynitrostilbenyl groups as NLO-chromophores, which constituted parts of the polymer backbones. The resulting polyimides 5–6 were soluble in polar solvents such as DMSO and DMF. Polymers 5–6 showed a thermal stability up to 300°C in TGA thermograms with T g values from DSC thermograms in the range of 135–141°C. The SHG coefficients (d 33) of poled polymer films were around 6.14 × 10−9 esu. The dipole alignment of poled polymer films exhibited exceptionally high thermal stability even at 30°C higher than T g and there was no SHG decay below 170–190°C due to the partial main chain character of polymer structure, which was acceptable for NLO device applications.
Acknowledgments
This work was supported by the Inje Research and Scholarship Foundation in 2004 and partly by the Korea Research Foundation Grant (KRF-2004-041-D00214).
Notes
a Determined from DSC curves measured on a TA 2920 differential scanning calorimeter with a heating rate of 10°C/min under nitrogen atmosphere.
b Determined from TGA curves measured on a DuPont 951 thermogravimetric analyzer with a heating rate of 10°C/min under nitrogen atmosphere.
a Polymer film after corona poling.
b SHG coefficients (d 33) were derived from the analysis of measured Maker-fringes [Citation10].
c Order parameter Φ = 1 − A1/A0, where A0 and A1 are the absorbances of the polymer film before and after corona poling, respectively.
d Film thickness was determined by the optical transmission technique [Citation9].