Synthesis and Properties of Novel Y-type Nonlinear Optical Polyester Containing Dioxynitroazobenzene Group with Enhanced Thermal Stability of Dipole Alignment

New Y-type polyester (3) containing nitrophenylazoresorcinoxy groups as NLO chromophores, which are components of the polymer backbone, was prepared and characterized. Polyester 3 is soluble in common organic solvents such as N,N-dimethylformamide and acetone. It shows a thermal stability up to 240 oC in thermogravimetric analysis with glass-transition temperature (Tg) obtained from differential scanning calorimetry near 116 oC. The second harmonic generation (SHG) coefficient (d33) of poled polymer film at the 1064 nm fundamental wavelength is around 4.63 × 10−9 esu. The dipole alignment exhibits a thermal stability even at 4 oC higher than Tg, and there is no SHG decay below 120 oC due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications