Synthesis and Nonlinear Optical Properties of Novel Polyester Containing Nitrophenylazonitroresorcinoxy Group

A new X-type polyester (4) containing nitrophenylazonitroresorcinoxy groups as NLO chromophores, which are components of the polymer backbone was prepared. Polyester 4 is soluble in common organic solvents such as N,N-dimethylformamide and dimethylsulfoxide. It shows a thermal stability up to 280°C from thermogravimetric analysis with glass-transition temperature (T_g) obtained from differential scanning calorimetry near 120°C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer films at the 1064 nm fundamental wavelength is around 5.08 × 10^?9 esu. The dipole alignment exhibits a thermal stability even at 5°C higher than T_g, and no SHG decay was observed below 125°C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.