Synthesis and electro-optic properties of novel Y-type polyester containing nitrothiazolylazoresorcinoxy group with highly enhanced thermal stability of dipole alignment

•Novel Y-type NLO polyester containing nitrothiazolylazoresorcinoxy group was prepared.•The resulting polymer shows a thermal stability up to 240 °C with Tg of 114 °C.•The SHG coefficient (d33) of the poled polymer film is near 3.58 p.m./V.•The polymer exhibits high SHG thermal stability up to 120 °C.

A novel Y-type polyester containing 4-(5-nitro-2-thiazolylazo)resorcinoxy groups as NLO chromophores, which are components of the polymer backbone, was prepared and characterized. The polyester is soluble in common organic solvents such as N,N-dimethylformamide and dimethylsulfoxide. It shows a thermal stability up to 240 °C in thermogravimetric analysis with glass-transition temperature (Tg) obtained from differential scanning calorimetry near 114 °C. The second harmonic generation (SHG) coefficient (d33) of a poled polymer film at the 1560 nm fundamental wavelength is around 3.58 p.m./V. The dipole alignment exhibits a thermal stability even at 6 °C higher than Tg, and there is no SHG decay below 120 °C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

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