Synthesis and Properties of Novel Nonlinear Optical Polyimide Containing Nitrophenylazoresorcinoxy Group

Abstract

New Y-type polyimide (4) containing nitrophenylazoresorcinoxy groups as NLO chromophores, which are components of the polymer backbone, was prepared and characterized. Polyimide 4 is soluble in common organic solvents such as N,N-dimethylformamide and dimethylsulfoxide. It shows a thermal stability up to 290°C in thermogravimetric analysis with glass-transition temperature (T_g) obtained from differential scanning calorimetry near 128°C. The second harmonic generation (SHG) coefficient (d ₃₃) of poled polymer film at the 1064 nm fundamental wavelength is around 5.46 × 10⁻⁹ esu. The dipole alignment exhibits a thermal stability up to T _g, and there is no SHG decay below 130°C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

Keywords:

• Differential scanning calorimetry (DSC)
• dipole alignment
• NLO
• polyimide
• SHG coefficient
• thermogravimetric analysis (TGA)

Acknowledgements

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (No. 2011-0026534).