• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.567-572
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• 1999

5-Nitro-2-(2'-vinyloxyethoxy)benzylidenemalononitrile (2a), methyl 5-nitro-2-(2'-vinyloxyethoxy)benzylidenecyanoacetate (2b), 3-nitro-4-(2'-vinyloxyethoxy)benzylidenemalononitrile (4a), methyl 3-nitro-4-(2'-vinyloxyethoxy)benzylidenecyanoacetate (4b), 2-nitro-5-(2'-vinyloxyethoxy)benzylidenemalononitrile (6a), and methyl 2-nitro-5-(2'-vinyloxyetboxy)benzylidenecyanoacetate (6b) were prepared by the condensation of 5-nitro-2-(2'-vinyloxyethoxy)benzaldehyde (1), 3-nitro-4-(2'-vinyloxyethoxy)benzaldehyde (3), and 2-nitro-5-(2'-vinyloxyethoxy)benzaldehyde (5) with malononitrile or methyl cyanoacetate, respectively. Vinyl ether monomers 2a-b, 4a-b, and 6a-b were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ethers) 7-9 having oxynitrobenzylidenemalononitrile and oxynitrobenzylidenecyanoacetate, which is effective chromophore for second-order nonlinear optical applications. Polymers 7-9 were soluble in common organic solvents such as acetone and DMSO. Tg values of the resulting polymers were in the range of 67-83 ℃. Electrooptic coefficient (r33) of the poled polymer films were in the range of 15-27 pm/V at 633 nm. Polymers 7-9 showed a thermal stability up to 300 ℃ in TGA thermograms, which is acceptable for NLO device applications.

• Journal of Photoscience
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• v.10 no.3
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• pp.251-255
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• 2003

The composites fabricated by blending nonlinear optical (NLO) chromophore such as {4-[2-(4-nitrophenyl)-vinyl] phenyl}diphenylamine (NVPDA) with photoconducting crosslinkable matrix, bis-(4-ethynylphenyl)-(4-octyloxy-phenyl)amine (BEOPEA), showed photorefractive property. Many problems faced in typical organic photorefractive systems such as time-consuming chemical synthesis, difficulty in rational design, intrinsic instability and phase separation could be avoided by this fabrication method.

• Korean Journal of Optics and Photonics
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• v.13 no.4
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• pp.356-362
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• 2002

The molecular orientational dynamics of the nonlinear optical(NLO) side-chain polymer N-(4-nitrophenyl)-(L)-prolinol-poly (pphenylene terephthalates) have been studied using nonlinear optical responses as measured by second harmonic generation (SHG). A new pulsed corona poling is used to orient the NLO chromophores and the polymer segments into the noncentrosymmetric structure required to obtain the SHG signal. By corona poling of negative high voltage pulses with variable repetition rates (between 0.5 and 10 ㎑) at temperature between 25$^{\circ}C$ and 80$^{\circ}C$, well below and about the glass transition temperature 70$^{\circ}C$, the side-chain chromophores and the polymer chain contour rearrange themselves and create the domain structure observed by atomic force microscopy(AFM). The pulsed corona voltage enhances the orientational ordering of the NLO chromophores and also significantly influences the growth of SHG signal and the improved relaxation behavior after the poling field is removed, reducing the visible damage to the polymer film dramatically. This new pulsed corona poling experiment gave direct in situ evidence that the NLO chromophore and the polymer backbone undergo anisotropic rearrangement during the poling process.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.704-709
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• 1998

Non-linear optical polymer based on poly (${\alpha}$-methylstyrene-co-maleic anhydride) (MSMA) substrate polymer was prepared by polymer reaction method and its thermal and electro-optic properties were examined. In the polymer reaction between MSMA substrate polymer and 2-[4-(4-nitrophenylazo)-N-ethylphenylamino]ethanol (DR1) chromophore, the degree of substitution of DR1 into MSMA was higher with the 4-dimethylaminopyridine (DMAP) as catalyst and 3-dicyclohexyl carbodiimide (DCC) as dehydrating agent (sample, MSMA-DC) than the one with just 4-dimethylaminopyridine as catalyst (sample, MSMA-D). The synthesized NLO polymer (MSMA-DC) exhibited electro-optic coefficient of 18 pm/V (632.8 nm) and glass transition temperature ($T_g$) of about $175^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1168-1171
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• 1998

Two kinds of second-order nonlinear optical copolymers were prepared by the copolymerization of the vinyl monomers containing NLO chromophore, methacrylic acid, and methyl methacrylate or butyl methacrylate. Glass transition temperatures (Tg of copolymers were around 130 ℃. The copolymers were soluble in common organic solvents such as tetrahydrofuran (THF), cyclohexanone, and N,N-dimethylformamide (DMF). The crosslinked copolymer was obtained by thermal treatment using pentaerythritol tetrakis(2-mercaptoacetate) as a crosslinker and became insoluble in tetrahydrofuran (THF) and N,N-dimethylformamide (DMF). Poling was carried out at 120 ℃ for 20 min and identified with UV-Vis spectroscopy. Electro-optic coefficient (r33) measurement showed a value of 35 pm/V for polymer 2 at 633 nm. Temporal stability of copolymers was improved owing to the crosslinked network, which was successfully obtained at 170 ℃ for 30 min after poling.

• Macromolecular Research
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• v.17 no.11
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• pp.874-878
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• 2009

Photorefractive polymer composites were synthesized based on poly (N-vinylcazbazole) (PVK) doped with liquid nonlinear optical chromophores and a sensitizer $C_{60}$. PVK/liquid NLO chromophores/$C_{60}$ devices showed no signs of phase separation and did not require a plasticizer, such as ethylcarbazole. The composites showed 69% diffraction efficiency (C3) and a rapid response time of 46 ms (C1) in four-wave mixing experiments at a light intensity of $60\;mW/cm^2$ and a wavelength of 633 nm.

• Macromolecular Research
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• v.11 no.4
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• pp.250-255
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• 2003

We prepared the photorefractive sol-gel glass based on organic-inorganic hybrid materials containing a charge transporting molecule, second-order nonlinear optical (NLO) chromophore, photosensitizer, and plasticizer. Carbazole and 2-{ 4-[(2-hydroxy-ethyl)-methyl-amino]-benzylidene}-malononitrile were reacted with isocyanato-triethoxy silane and the functionalized silanes were employed to fabricate the efficient photorefractive media induding 2,4,7-trinitrot1uorenone (TNF) to form a charge transfer complex. The prepared sol-gel glass samples showed a large net gain coefficient and high diffraction efficiency at a certain composition. As the concentration of photosensitizer increased, the photorefractive properties were enhanced due to an increment of charge carrier density. Dynamic behavior of the diffraction efficiency was also investigated with the concentration of the photosensitizer.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.77-84
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• 2005

We prepared the new nonlinear optical chromophores that show fairly high microscopic nonlinearity through intramolecular charge transfer. Phenothiazine and carbazole units played an important role to contribute high electron donability and connect the resonance pathway via conjugative effect in the cyclized ring beside the aromatic ring. Theoretical calculation, electrochemical analysis, and absorption spectroscopic study gave us useful information about the energy states and microscopic nonlinearities of two serial chromophores. We compared the microscopic nonlinearities of four chromophores with the conjugation length and electron donability in the push-pull type NLO chromophores. The effect of gradient donability and lengthening the conjugation were investigated on the electronic state and microscopic nonlinearity.

• Macromolecular Research
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• v.15 no.3
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• pp.234-237
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• 2007

3,4-Bis-(3,4-dicarboxyphenylcarboxyethoxy)-4'-nitrostilbene dianhydride was prepared and reacted with 4,4'-(hexafluoroisopropylidene)dianiline to yield a novel Y-type polyimide containing the 3,4-dioxynitrostilbenyl group as an NLO-chromophore, which constituted part of the polymer backbone. The resulting polyimide was soluble in polar solvents such as acetone and N,N-dimethylformamide. The polymer exhibited good thermal stability up to $370^{\circ}C$ in the thermogravimetric analysis. The glass-transition temperature ($T_g$) obtained from the differential scanning calorimetry thermogram was near to $153^{\circ}C$. The second harmonic generation (SHG) coefficient ($d_{33}$) of the poled polymer film at the fundamental wavelength of $1064\;cm^{-1}$ was around $2.15\;{\times}\;10^{-8}\;esu$ (9.01 pm/V). The dipole alignment exhibited exceptionally high thermal stability even at a temperature $30^{\circ}C$ above the $T_g$, and there was no SHG decay below $180^{\circ}C$ because of the partial main chain character of the polymer structure.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.355-361
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• 1999

We have synthesized the soluble polymide based side chain system with covalently attached NLO chromophore Disperse Red 1. The developed polymer is optically transparent in the range of optical communication wave-lengths. Its glass transition temperature$(T_g)$ and thermal decomposition temperature$(T_d)$ are $225^{\circ}C, 310^{\circ}C$ respectively. The poled film with the poling field of $100 V/\mu\textrm{m}$ shows that the dielectric constant is 3.37 at the 10-kHz frequency, the refractive indices of TM and TE modes are both 1.631 at $\lambda = 1300 nm$, and the Electro-optic coefficients are 4.6~9.2 pm/V at $\lambda = 1300 nm$. There are no decays of the EO coefficient in the poled polymer at $180^{\circ}C$ in one hour, and $90^{\circ}C$ in 500 hours.