The design, synthesis, and nonlinear optical properties of novel X-type polyurethane containing dicyanovinylnitroresorcinoxy group with enhanced SHG thermal stability

Article abstract of DOI:10.1002/pola.26405

Novel X-type polyurethane 5 containing 4-(2′,2′-dicyanovinyl)- 6-nitroresorcinoxy groups as nonlinear optical (NLO) chromophores, which constitute parts of the polymer backbone, was prepared and characterized. Polyurethane 5 is soluble in common organic solvents such as acetone and N,N-dimethylformamide. It shows thermal stability up to 280 C from thermogravimetric analysis with a glass transition temperature (T_g) obtained from differential scanning calorimetry thermogram of around 120 C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer film at 1064-nm fundamental wavelength is around 6.12 × 10^-9 esu. The dipole alignment exhibits a thermal stability even at 5 C higher than T_g, and there was no SHG decay below 125 C due to the partial main chain character of the polymer structure, which is acceptable for NLO device applications.