The influence of pentafluorophenyl groups on the nonlinear optical (NLO) performance of high generation dendrons and dendrimers
With the aim to make the influence of pentafluorophenyl groups in the periphery of high generation dendrons and dendrimers on their NLO performance clearly, some NLO dendrons and dendrimers with different chromophore moieties or different end-capped groups were carefully designed and investigated in detail. The results demonstrated that some strong Ar-ArF interactions between the pentafluorophenyl groups in the periphery and the normal phenyl rings of the donors, could influence the topological structures of dendrons or dendrimers, and then affect their NLO performance. Furthermore, the optical transparency and the stability of the dendrons and dendrimers with pentafluorophenyl groups as end-capped moieties were all improved, in comparison with normal dendrons and dendrimers containing phenyl ones as the end-capped groups.
Star-shaped azo-based dipolar chromophores: design, synthesis, matrix compatibility, and electro-optic activity.
Three new azo-benzene-based push-pull chromophores with dendritic architecture were synthesized as active materials for electro-optic applications. These chromophores were synthesized in six or seven synthetic steps with an overall yield of around 80% per step and high purity. UV-vis spectroscopy showed significant influence of the transient dipole moment on the observed r(33) values. The chromophores were stable to photochemical oxidation in ambient light and air. The electrical poling conditions were optimized for each chromophore as the T(g) of the composite material varied significantly. The highest EO coefficient achieved was 22-25 pm/V at 1550 nm wavelength. STEM analysis of the blends enabled the correlation of the activity of these large chromophores with the blend morphology. An amorphous polycarbonate host effectively disperses the chromophores in 2-20 nm aggregates in the active materials. However, macrophase separation into 200-500 nm aggregates was observed in a methacrylate host matrix.
Synthesis and optical properties of new fluorinated second-order nonlinear optical copolymers: an attempt toward the balance between solubility and long-term alignment stability
A new fluorinated co-polyarylate (P) was synthesized by interfacial polymerization of 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,2-trifluoroethane (BPAPF) and diphenolic acid (DPA) with isophthaloyl chloride (IPC). P1–P3, containing different concentrations of tricyanofuran (TCF) accepter chromophores, were obtained by the esterification reaction between P and chromophore 1 catalyst by DCC and DPTS. The obtained co-polyarylates were characterized and evaluated by UV-Vis, 1H NMR, FT-IR, GPC, DSC and TGA. All the co-polyarylates P1–P3 exhibited excellent thermal stability, film forming ability and good electro-optic (EO) activity. The largest r33 value of the copolymers is 52 pm V−1 at the wavelength of 1310 nm, when the concentration of chromophore 1 is 18 wt%.