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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 289-291 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Large third-order optical nonlinearity was found with the soluble conjugated polymers (substituted polyacetylenes) synthesized by the ring-forming metathesis polymerization of 4,4-disubstituted-1,6-heptadiynes. These polymers were of quite high molecular weight (∼105) and were highly soluble in common organic solvents. The linear optical property and the third-order optical nonlinearity of these polymers were investigated in terms of the chemical structure of the 4,4-disubstituents using the polymer films of around 100-nm thickness fabricated by the spin coating of tetrahydrofuran solutions. The π-π* transition of the conjugated π-electron main chain was characterized as the strong absorption peak at around 540 nm of the electronic spectra, where the optical density of the transition was found to be largely dependent on the molar volume of the substituents. The near-resonant values of the third-order nonlinear optical coefficient, χ(3)(−3ω;ω,ω,ω) were found to be 2.6 to 6.5×10−11 esu, which also were controlled by the molar volume of the substituent group.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 190-192 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two-component organic glasses consisting of photoconductive molecule, N′-[9-(2-ethylhexyl)-9H-carbazol-3-ylmethylene]-N,N-diphenyl-hydrazine (EHCzHy), and multifunctional photorefractive molecules, 9-(2-ethyl-hexyl)-3-[2-(4-methanesulfonyl-phenyl)-vinyl]-9H-carbazole (EHCS) [J. Sohn et al., Appl. Phys. Lett. 77, 1422 (2000)] and 9-(2-ethylhexyl)-3-[2-(4-nitro-phenyl)-vinyl]-9H-carbazole (EHCN), were prepared, and their charge carrier mobility and photorefractive grating buildup were investigated. EHCzHy is a unipolar hole-transporting (μh=4.16×10−6 cm2/V s) molecule with no electro-optic property. EHCS and EHCN are nonlinear optical molecules with unipolar (μh=2.42×10−6 cm2/V s) and bipolar (μh=2.30×10−6 cm2/V s,μe=2.86×10−6 cm2/V s) carrier mobilities, respectively. Different behaviors of the photorefractive grating buildup in two-component organic glasses were investigated as a function of EHCN or EHCS content. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1422-1424 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 9-(2-Ethyl-hexyl)-3-[2-(4-methanesulfonyl-phenyl)vinyl]-9H-carbazole (EHCS) was synthesized as a monolithic photorefractive molecule forming low Tg(∼25 °C) organic glass. It showed distinct photoconductivity due to the carbazole moiety and the optical nonlinearity by the push–pull structure. The EHCS glass showed excellent optical quality and great stability as the ethylhexyl group effectively suppressed the crystallization in the films. Also, the extremely simple structure of EHCS contributed to a very high chromophore concentration. This single-component photorefractive glass of EHCS showed large net gain (56.3 cm−1) and diffraction efficiency (12%). Photorefractivity of EHCS glass was greatly improved by doping with a small amount (〈1%) of 2,4,7-trinitrofluorenone (TNF). The two-beam coupling gain of samples with TNF was 113 cm−1 and the diffraction efficiency was 29%. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Two nonlinear optical (NLO) methacrylate monomers, 2-methyl-acrylic acid 2-(ethyl-{4-[2-(6-nitro-quinolin-2-yl)-vinyl]-phenyl}-amino)-ethyl ester (5) and 2-methyl-acrylic acid 6-{3-[2-(6-nitro-quinolin-2-yl)-vinyl]-carbazol-9-yl}-hexyl ester (7) were newly synthesized and copolymerized with methylmethacrylate to give NLO polymers, P1 and P2. These polymers were well soluble in organic solvents and showed glass transition temperatures at 145 °C and 114 °C, respectively. The number average molecular weights (Mn) were 26,600 for P1 and 9,300 for P2. The SHG coefficients (d33) of corona-poled films of P1 and P2 measured with 1.064 μm Nd-YAG laser were 32.2 pm/V and 17.6 pm/V, respectively.
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  • 5
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Novel class of p-phenylenevinylene copolymer with sulfonylene group in the main chain (PPVS) was synthesized through the Wittig reaction of bis(bromomethyl-p-phenyl)-sulfone triphenylphosphonium salt with terephthaldehyde. PPVS was highly soluble in common organic solvents and showed strong blue-shifted fluorescence because the polar sulfonylene group provided better solubility and limited π-conjugation in polymer chain. A single layer device with PPVS sandwiched between indium-tin-oxide (ITO) and aluminum electrodes showed a blue electroluminescence (EL) peaked at 470 nm under the threshold voltage of 14 V. HOMO and LUMO levels of PPVS were found to be 0.46 and 0.28 eV, respectively, lower than those of poly(p-phenylenevinylene) (PPV).
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Second-harmonic generation (SHG) has been studied for understanding the enhancement mechanism for the second-order optical nonlinearity by the nematic (or axial) ordering in a liquid crystal doped with one-dimensional nonlinear optical (NLO) organic molecules. An extended version of the Maier-Saupe mean-field theory for nematic liquid crystals was developed to obtain analytical expressions for the second-order NLO coefficients in terms of the axial order, the polar order and the effective nematic potential. From the SHG data in a guest-host system composed ofN,N'-dimethylaminonitrostilbene molecules (0.5% by weight) and a liquid crystal, the enhancement of the second-order NLO coefficient,d 33, by nematic ordering becomes almost 3, which agrees well with our theoretical predictions.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2841-2850 
    ISSN: 0887-624X
    Keywords: poly(ethylene terephthalate) ; poly(ethylene 2,6-naphthalate) ; polymer blends ; transesterification ; miscibility ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of transesterification on the miscibility of poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) were studied. Blends were obtained by solution precipitation at room temperature to avoid transesterification during blend preparation. The physical blends and transesterified products were analyzed by wide-angle x-ray scattering, differential scanning calorimetry, and nuclear magnetic resonance spectroscopy. It was found that the physical blends are immiscible and when the extent of transesterification reaches 50% of the completely randomized state, independent of blend composition, the blends are not crystallizable and show a single glass transition temperature between those of starting polymers. The interchange reactions were significantly influenced by annealing temperature and time but negligibly by blend composition. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 9-14 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Second-order nonlinear optical copolymer containing p-hydroxyphenyl maleimide as a comonomer was newly synthesized. Second-order nonlinear optical properties of the poled films were investigated in terms of the second harmonic generation (SHG) and linear electrooptic (EO) coefficient measurement. SHG coefficient, d33 was found to be 14 pm/V at the fundamental wavelength of 1064 nm and EO coefficient, r33 was found to be 25-30 pm/V at 633 nm wavelength. To prevent the orientational relaxation of poled polymer, the thermal crosslink reaction was induced using diisocyanate as a crosslinker between the side chains themselves. Temporal stabilities of second-order NLO coefficients of crosslinked polymer systems were proved much better than that of guest-host system or other side chain polymers. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 9
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new polymer containing a heterocyclic quinoline unit in the main chain, poly[4-phenyl-2,6-(p-phenoxy) quinoline] (PQ), was synthesized by an acid-catalyzed self-condensation reaction. We have found that PQ, which is generally a good insulator itself, can show photoconductivity when doped with an electron acceptor. From the UV-VIS absorption spectra, we found that PQ can form a charge-transfer (CT) complex with an electron acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The CT complex of the PQ-DDQ mixture showed distinct photoconductivity. Employing the DDQ composition ranging from 5 to 10 wt %, the ratio of dark and photoconductivity was calculated to be about 1 : 100 at an applied electric field of 105 V/cm. Additionally, the bilayer sample of PQ/DDQ exhibited a significant photovoltaic effect. The photovoltaic current increased with increasing photointensity. The open-circuit voltage was measured ranging from 0.4 to 0.7 V and the photovoltaic conversion efficiency was calculated to be 10-3-10-2%. The PQ film treated with DDQ vapor showed a relatively higher photovoltaic effect than that of the sample treated with DDQ solution. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1-7 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: New heteroaromatic polymer containing quinoline unit in the main chain, poly[2,6-(p-phenoxy)-4-phenyl quinoline] (PQ), was synthesized by the acid-catalyzed self-condensation reaction [Friedländer quinoline synthesis] of 4-amino-4′-acetyl-3-benzoyldiphenyl ether, and its chemical structure was characterized by IR and NMR spectra and also by elemental analysis. The PQ was soluble in common organic solvents such as chloroform or tetrahydrofuran; thus a strong coherent film of this polymer could be easily prepared from the solution by the casting or spin-coating technique. Attributing to the wholly aromatic chemical structure, PQ appeared an extremely high thermal stability as to show no weight loss up to 550°C both in air and nitrogen atmosphere. From the UV-VIS absorption spectra, we found that PQ had a strong tendency to form the charge transfer (CT) complex with electron acceptors such as 2,4,7-trinitrofluorenone (TNF). The CT complex film of PQ-TNF showed a good photoconductivity even under the ambient room illumination and was utilized for the fabrication of photovoltaic device whose conversion efficiency was around 10-2%.
    Additional Material: 7 Ill.
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