Papers by Author: Feng Xian Qiu

Abstract: A new chromophore containing azo group, 3,3'-dichloro-4,4'–di-(4-amino-azo-phenyl) -diphenylmethane (CAAPM), was synthesized based on 3,3'-dichloro-4,4'-diamino– diphenylmethane, sodium nitrite and benzenamine via diazo-coupling reaction. Azobenzene polyurethane (PU) containing chiral unit was obtained from CAAPM, chiral reagent L(-)-tartaric acid and isophorone diisocyanate (IPDI). The chemical structures of CAAPM and PU were characterized by FT-IR and UV-Vis spectroscopy. The measurements of refractive index (n) and thermo-optic coefficient (dn/dT) of polyurethane were demonstrated at complex light. The values of n and dn/dT were used to calculate the dielectric constant (ε) and its variation with temperature (dε/dT). The dn/dT is 4.2000～-3.7000×10^-4°C^-1. The conclusion has a little significance to develop new the digital optical switch (DOS).

Abstract: A novel chromophore molecule (HEPNBT) was synthesized by diazo-coupling reaction. The polyurethane (HEPU) was obtained from chromophore molecule HEPNBT, NJ-220 and isophorone diisocyanate (IPDI). The structures of HEPNBT and HEPU were characterized using the Fourier transform infrared and UV-visible spectroscopy. The refractive index (n) of HEPU was determined at different temperature and wavelength (532nm, 650nm and 850nm) using attenuated total reflection (ATR) technique, and the thermo-optic coefficient (dn/dT) was -4.149×10^-4 °C^-1(532nm), -7.954×10^-4°C^-1 (650nm) and -6.71^{Superscript text}4×10^-4°C^-1 (850nm), res^{Superscript text}pectively. Using the CCD digital imaging devices, transmission loss of HEPU was measured and the value was 0.238 dB/cm. The results show that the obtained HEPU has a certain significance to the development of new types of digital thermo-optic switch material.

Abstract: A monomer 4,4'-bis(β-hydroxyethyl)biphenyl (2BP) was synthesized by the Williamson reaction from 2-chloroethanol and 4,4'-biphenol. Then, the novel dendritic liquid crystal macromolecule (DLCM) containing biphenyl structure was synthesized with 2BP and 1,3,5-benzenetrimethylacylchloride as monomers by dispersion method. The structures of 2BP and the DLCM were characterized by FT-IR and 1H-NMR. The thermal stabilities of he DLCM were measured by TGA and DSC. The results showed that the DLCM had good thermal stability and the DLCM may have a higher phase inversion temperature.

Abstract: Nonlinear optical (NLO) polyimide and a series of polyimide/silica nanohybrids were synthesized from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), NLO molecule 4-(4’- nitrophenyl-2-yl) phenyl-1,3-diamine, coupling agent and TEOS via sol-gel method. The TEOS content in the hybrids was varied from 0 to 22.5 wt%. The prepared hybrids were characterized by FT-IR, Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM). The glass transition temperature (Tg) and the decomposition temperature (Td) at 5 % mass loss were in the range 232~365 °C and 335~475 °C, respectively. The results showed that the prepared materials had excellent thermal stabilities. The electro-optic coefficients (γ33) at 832 nm were in the range of 19-34 pm/V and the values remained well. The experimental results indicate that the prepared thin films have good candidate for electro-optical applications.

Abstract: A novel polyelectrolyte (PLJY) was synthesized based on the azobenzene chromophore containing functional groups (-C=C-) and α-methacrylic acid by radical polymerization. The PLJY was characterized by FT-IR and UV-vis spectroscopy. The thermal property was characterized using the differential scanning calorimeter (DSC). The glass transition temperatures (Tg) was 179.1 oC and showed that the PLJY had excellent thermal stability. Influences of pH values on the UV-Vis absorption spectra of PLJY were studied and polyelectrolyte solution had good pH-sensitivity and H-aggregation behavior. The photoresponsive and thermochromism behaviors were investigated for the azo polyelectrolyte PLJY solution or film. By 256 nm excitation wavelength, the PLJY solution or film appeared photo responsive behavior. At high temperature, the PLJY solution had thermochromic behavior. These results showed that the polyelectrolyte had potential applications in optical information storage and optical switch.

Abstract: A novel azobenzene optically polymer (P-DA) was synthesized based on the azo chromophore molecule, chiral reagent L(-)-tartaric acid, acryloyl chloride and methacrylate. The P-DA was characterized by FT-IR, UV-Vis spectroscopy, 1H NMR, DSC and TGA. The P-DA had high thermal stability up to its glass-transition temperature (Tg) of 110 oC and 5 % heat weight loss temperature of 199 oC. The UV-induced trans/cis photoisomerization and reflex-isomerization behaviors were investigated. The results indicated that the P-DA solution could undergo photochromism after irradiated by 365 nm UV light. The optical parameters: refractive index (n), the dielectric constant (ε) and thermal volume expansion coefficient (β) of P-DA were obtained. The thermo-optic coefficients are one order of magnitude larger than those of the inorganic materials, such as SiO2 (1.1×10−5 oC -1 and LiNbO3 (4×10−5 oC -1) and was larger than the organic material such as polystyrene (-1.23×10-4 oC -1) and PMMA (-1.20×10-4 oC -1). The conclusion had a little significance to develop optical communication.

Abstract: A novel azobenzene polyelectrolyte (ABAPE) was synthesized based on chromophore 4-(4’-nitrophenylazo) naphthol (NPAN), epoxychloropropane and α-methacrylic acid. The ABAPE was characterized by FT-IR and UV-vis spectroscopy. The aggregation behaviors of ABAPE were investigated based on different pH values by the UV-vis spectroscopy. The isomerization behavior of the ABAPE in DMAC solution was studied by 256 nm UV irradiation light. Attenuated total reflection (ATR) method was adopted and carried out the measurement of refractive index of the thin film. The thermo-optic coefficient (dn/dT) was -2.9228×10-4°C-1 and was bigger than inorganic materials such as silica glass, zinc silicate glass, borosilicate glass and the organic materials of polystyrene and PMMA. These results showed that the polyelectrolyte could be used to carry out optical storage and thermo-optic switch.

Abstract: An intercalation nonlinear-optical (NLO) polyimide was synthesized based on the 3,3’, 4,4’- Bisphenyltetracarboxylic (BPDA) and [(6-nitrobenzothiazole-2-yl)diazenyl]phenyl-1,3- diamine (NBADA). Then, hybrid polymer was synthesized by the sol-gel technique. FT-IR spectroscopy and 29Si NMR were used to characterize the structure of the hybrid. The results revealed that Q3, Q4 and T3 are the major microstructure elements in forming a network structure. The surface morphology, particle size, crystallinity and the thermal stability of the hybrid were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). DSC and TGA results showed that the glass transition temperature (Tg) and the decomposition temperature (Td) at 5% mass loss were 243, 359°C and 355, 456°C, respectively. These results showed that the hybrid material had excellent thermal stability than the pure polyimide. The electro-optic coefficients of nonlinear optical polyimide and hybrid were measured at the wavelength of 832 nm. The electro-optic coefficients were 22 and 19pm/V (poling voltage of 3.8KV, 210°C) and the values remained well (retained＞93% for more than 100h). The results suggest that the materials have potential applications for high performance optical device.