Synthesis of Poly (3-acetylpyrrolyl methine) with Azobenzene Side Groups and Study on Its Third-order Nonlinear Optical Property

A novel soluble 7r-conjugated polymer, poly [(3-acetylpyrrole-2, 5-diyl) p-(N, N-dimethylamino) azobenzylidene] (PA-PDMAABE), was synthesized by condensation of 3-acetylpyrrole with 4-aldehyde-4’-dimethylaminoazobenzene (AD-MAA). The chemical structure of PAPDMAABE was characterized by Fourier transform infrared spectroscopy (FTIR),1H-NMR, and UV-Vis-NIR spectra. Transmission electron microscope (TEM) analysis for PAPDMAABE indicatesthat part of PAPDMAABE is in crystal state, due to the short-range order of the polymer. Thermogravimetric analy-sis (TGA) curve shows that the polymer has good thermal stability and its decomposition temperature is 248°C. Theoptical band gap of PAPDMAABE obtained from the optical absorption spectrum is about 1.73 eV. The resonantthird-order nonlinear optical property of PAPDMAABE at 532 nm was studied using degenerate four-wave mixing(DFWM) technique. The resonant third-order nonlinear optical susceptibility of the polymer is about 7.48×10-8 esu.