Synthesis and properties of nonlinear optical novel polyurethane containing nitrothiazolylazoresorcinoxy group

ABSTRACT

A new Y-type polyurethane (4) containing nitrothiazolylazoresorcinoxy groups as NLO chromophores, which are components of the polymer backbone was prepared. Polyurethane 4 is soluble in common organic solvents such as N,N-dimethylformamide and dimethylsulfoxide. It shows a thermal stability up to 240°C from thermogravimetric analysis with glass-transition temperature (T_g) obtained from differential scanning calorimetry near 126°C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer films at the 1064 nm fundamental wavelength is around 9.02 × 10⁻⁹ esu. The dipole alignment exhibits a thermal stability even at 4°C higher than T_g, and no SHG decay was observed 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
• polyurethane
• SHG coefficient
• thermogravimetric analysis (TGA)

Acknowledgments

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2015R1D1A1A09058972).