Synthesis and characterization, second-order nonlinear optical and photorefractive properties of new multifunctional polysiloxane with broad optical transparent pentafluorophenyl azo chromophore

摘要

A new polysiloxane P1 with pendant carbazoly groups and a high density of the pentafluorophenyl azo chromophore as side chain was synthesized in moderate yield by two successive postfunctionalization reaction including Vilsmeir formy-lated reaction and Knoevenagel condensation. Its structure was verified by ~1H NMR, IR, and UV-Vis spectra. The polymer P1 exhibited good solubility in common organic solvents and was thermally stable up to 282℃. The maximum absorption appeared at about 407 nm for P1 in THF, which was blue-shifted about 87 nm compared to the corresponding polysiloxane P2 with a well-known nitro acceptor azo chromophore, resulting in a wider transparency window. The value of the NLO coefficient d_(33) of P1 thin film, measured by in situ second harmonic generation (SHG), was 11.9 pm/V. Preliminary photorefractive experiments showed that P1 obtained diffraction efficiency of 78% and a time constant of 1.19 sec.