Guorong Cao

Helical Biphenyl Bisazo Polyurethane: Preparation, Characterization and Analysis of Polymeric Thermo-Optic Switch

The bisazo chromophore molecule (CAAPM) and helical biphenyl bisazo polyurethane (HBBPU) were synthesized. The structures of CAAPM and HBBPU were characterized by FT-IR and UV-vis spectroscopic techniques. The measurements of refractive index and thermo-optic coefficient (dn/dT) of HBBPU were demonstrated at different wavelengths and different temperatures by the ATR technique. By using CCD digital imaging devices, transmission loss of the internal waveguide was measured. The refractive index dispersions and Sellmeyer coefficients of HBBPU were obtained by the Sellmeyer equation. A Y-branched switch based on the thermo-optic effect was proposed and the performance of the switch was simulated. With a branching angle of 0.143° and the FD-BPM method, the result showed that the power consumption of the thermo-optic switch could be only 3.6 mW, and the response time of the switch could reach about 8 ms. This is a significant improvement in reducing power consumption compared with the normal Y-branched polymer thermo-optic switch.

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.

Synthesis and electro-optic property of intercalation polyimide and polyimide/ silica

An intercalation nonlinear-optical (NLO) polyimide was synthesized by the ring-opening polyaddition of 4,4-(Hexafluoroisopropylidene) diphthalic Anhydride (6FDA) and [(6-nitrobenzothiazol-2- yl)diazenyl]phenyl-1,3-diamine. Then, sol-gel technique was adopted, utilizing 3- aminopropyltriethoxysi- lane (APTES) and tetraethoxysilane (TEOS). The polyimide/silica hybrid material was obtained. The polyimide and hybrid were characterized by the methods of FT-IR spectra, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) to get their structure, morphology, thermal performance etc. The results showed that interpenetrating hybrid polymer networks was formed, there were finely dispersed, and existed bond conjunction between organic-inorganic phases. The glass transition temperature (Tg) and the decomposition temperature (Td) at 5% mass loss were 247, 364degC and 363, 462degC, respectively. These results showed that the hybrid material had excellent thermal stability than the pure polyimide. The polyimide and hybrid solution could be spin coated on the indium-tin-oxide (ITO) glass to form optical quality thin films. The electro-optic coefficients of nonlinear optical polyimide and hybrid were measured at the wavelength of 832 nm. The electro-optic coefficients (gamma33) were 19 and 16 pm/V and the values remained well (retained Gt92% for more than 100 h). The results suggest that the materials have potential applications for high performance optical device.

Preparation, characterization and electro-optic properties of polyimide/SiO 2 nanohybrid materials

A series of the polyimide-silica NLO nanohybrid materials were synthesized from 3,3, 4,4- Bisphenyltetracarboxylic (BPDA), 2,2-Bis(3-amino-4-hydroxyphen-yl) hexafluoropropane (6FHP), nonlinear optical (NLO) molecule 4-(N-2-Hydroxyethyl-N-methylamino)-4-[(6-nitroben-zothiazol-2-yl)-diazenyl] azobenzene (HNBDA), coupling agent APTES and hydrolysate of TEOS via sol-gel process. The TEOS contents in the hybrids were varied from 0 to 22.5/wt%. The prepared polyimide/silica hybrids were characterized by FT-IR, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) etc. The glass transition temperature (Tg) and the decomposition temperature (Td) at 5% mass loss were in the range 215~364degC and 320~430degC, respectively. These results showed that these hybrid materials had excellent thermal stability. The hybrid solutions could be spin coated on the indium-tin-oxide (ITO) glass to form optical quality thin films. The electro-optic coefficients (gamma33) at 832 nm for polymer poled were in the range of 21-50 pm/V and the values remained well (retained > 88% for more than 100 h). The experimental results suggest that the hybrid thin films have potential applications as passive films for optical devices.