Preparation of novel azo polyurethane with chiral atoms and its optical properties

A new azo polyurethane with chiral atoms was synthesized with 4-nitroaniline, sodium nitrite and S(-)-α-methylbenzylamine by diazo coupling reaction. The absorption spectrum of this novel azo polyurethane with chiral atoms was characterized by UV-Vis spectroscopy. The solubility was measured with different kinds of organic solution. And the thermal property was characterized by X-5 micro melting point apparatus, by which the melting point is 165°C. This result showed that the new azo polyurethane had excellent thermal stability. Mechanical properties of the novel polyurethane with chiral atoms, such as tensile strength and hardness, were also studied. The refractive index of the polymer waveguide thin film was detected by attenuated total reflection (ATR) method at different temperature, wavelength and mode of the incident light. The results showed that the refractive index of the material decreases with the temperature rising. Compared with inorganic materials, the new material has a bigger thermo-optic coefficient. At the same time, the dispersion coefficient was calculated by the Sellmeyer equation. The thermo-optical coefficients of the material for TM (transversal magnetic) and TE (transversal electric) modes were also studied and they are obviously different, which can be used to design and develop the novel thermo-optic switch and even all-optical switch in the future.