Synthesis and properties of nonlinear optical novel polyurethane containing nitrothiazolylazoresorcinoxy group

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 degrees C from thermogravimetric analysis with glass-transition temperature (T-g) obtained from differential scanning calorimetry near 126 degrees C. The second harmonic generation (SHG) coefficient (d(33)) of poled polymer films at the 1064nm fundamental wavelength is around 9.02 x 10(-9) esu. The dipole alignment exhibits a thermal stability even at 4 degrees C higher than T-g, and no SHG decay was observed below 130 degrees C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.