Synthesis and Nonlinear Optical Properties of Novel Y-type Polyurethane Containing Nitroazobenzene Group

Abstract

Novel Y-type polyurethane 3 containing 4-(4-nitrophenylazo)resorcinoxy groups as nonlinear optical (NLO) chromophores, which constitute part of the polymer backbone, was prepared and characterized. Polyurethane 3 is soluble in common organic solvents such as acetone and N,N-dimethylformamide. It shows thermal stabilities up to 270°C from thermogravimetric analysis with glass transition temperature obtained from differential scanning calorimetry of 102°C. The second harmonic generation (SHG) coefficient (d ₃₃) of poled polymer film at 1064 nm fundamental wavelength is 4.92 × 10⁻⁹ esu. Polymer 3 exhibits a high thermal stability even at 8°C higher than T _g, and no significant SHG decay is observed below 110°C, which is acceptable for nonlinear optical device applications.

Keywords:

• Differential scanning calorimetry (DSC)
• dipole alignment
• NLO
• polyurethane
• 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).