• Polymer(Korea)
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• v.26 no.2
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• pp.253-259
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• 2002

The objective of this study is to obtain thermally stable and low optical loss polymers for optical waveguiding materials. The crosslinkable poly (maleimide-co-methacrylate)s were synthesized using a pentafluorophenylmaleimide (an optical loss reducer), two methacrylate derivatives (refractive index controllers), and a glycidylmethacrylate (a crosslinker). These copolymers exhibited good thermal stability and could be thermally crosslinked by heat treatment. The refractive indexes of the copolymers could be precisely controlled by the variation of comonomer feed ratio, which was in the range of 1.45 ~ 1.49. These copolymers had very low birefringence of $6{ imes}10^{-4}$ ~ $1{ imes}10^{-4}$. These copolymers were crosslinked by contact printing and then developed by wet etching to obtain high quality waveguide pattern.

• Macromolecular Research
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• v.13 no.6
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• pp.491-498
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• 2005

Fluorene-containing, spiro-type, conjugated polymers were synthesized via the cyclopolymerization of dipropargylfluorenes (2-substituted, X=H, Br, Ac, $ NO_{2}$) with various transition metal catalysts. The polymerization of dipropargylfluorenes proceeded well using Mo-based catalysts to give a high polymer yield. The catalytic activities of the Mo-based catalysts were found to be more effective than those of W-based catalysts. The palladium (II) chloride also increased the polymer yield of the polymerization. The polymer structure of poly(dipropargylfluorene)s was characterized by such instrumental methods as NMR ($^{1}H_{-}$, $^{13}C_{-}$), IR, UV-visible spectroscopies, and elemental analysis as having the conjugated polymer backbone bearing fluorene moieties. The $^{13}C_{-}$NMR spectral data on the quaternary carbon atoms in polymers indicated that the conjugated cyclopolymers have the six-membered rings majorly. The poly(dipropargylfluorene) derivatives were completely soluble in halogenated and aromatic hydrocarbons such as methylene chloride, chloroform, benzene, toluene, and chlorobenzene. The poly(dipropargylfluorene) derivatives were thermally more stable than poly(dipropargylfluorene) itself, and X-ray diffraction analyses revealed that the polymers are mostly amorphous. The photoluminescence peaks of the polymers were observed at about 457-491 nm, depending on the substituents of fluorene moieties.

• Macromolecular Research
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• v.17 no.11
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• pp.912-918
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• 2009

An optically active diacid containing the L-histidine moiety was prepared by reacting pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic acid 1,2,4,5-dianhydride) 1 with L-histidine 2 in acetic acid, and was polymerized with several aromatic diamines 5a-g to obtain a new series of optically active poly(amide-imide)s (PAIs) using two different methods, such as direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP)/triphenyl phosphite (TPP)/calcium chloride ($CaCl_2$)/pyridine (Py) and direct polycondensation in a tosyl chloride (TsCl)/pyridine (Py)/N,N-dimethylformamide (DMF) system as a condensation agent. The resulting new polymers 6a-g with inherent viscosity was obtained in good yield. The polymers were readily soluble in polar organic solvents, such as N,N-dimethyacetamide (DMAc), N,N-dimethyformamide (DMF), and dimethyl sulfoxide (DMSO). The obtained polymers were characterized by FTIR, specific rotation, elemental analysis as well as $^1$H-NMR spectroscopy and gel permeation chromatography (GPC). The thermal stability of the resulting PAIs was evaluated with thermogravimetric analysis techniques under a nitrogen atmosphere.

• Bulletin of the Korean Chemical Society
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• v.20 no.6
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• pp.677-682
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• 1999

Conjugated polycarbosilanes with diacetylene and aromatic groups of thiophene or phenylene simultaneously present in the polymer backbone such as poly[[1,4-bis(thiophenyl)buta-1,3-diyne]-alt-(dimethylsilane)], poly[[1,4-bis(thiophenyl)buta-1,3-diyne]-alt-(diphenylsilane)], poly[[1,4-bis(phenyl)buta-1,3-diyne]-alt-(dimethylsilane)],and poly[[1,4-bis(phenyl)buta-1,3-diyne]-alt-(diphenylsilane)] have been prepared. The characteristic C=C stretching frequencies appear at 2177-2179㎝-1 in the IR spectra of the polymers. The molecular weights of these polymers were detemined by GPC. All of these materials are soluble in organic solvents such as THF and chloroform, and thermally stable up to 200℃ in general without any weight loss under nitrogen. The prepared materials in THF solvent show a maximum absorption peak in the range of 334-356 nm with a molar absorptivity of 10³∼10ⁿ(n=5)L/(cm·mol) in the UV-visible absorption spectra. A maximum emission peak in the range of 403-550 nm is also observed in the fluorescence emission spectra. Both absorption and emission spectra strongly indicate that the obtained polycarbosilanes contain the new conjugated systems along the polymer main chain.

• Macromolecular Research
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• v.17 no.2
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• pp.84-90
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• 2009

We prepared side-chain liquid crystalline polymers comprising two monomeric units, one having a mesogenic side group that could form a smectic mesophase and the other having a phenolic group attached to the polymer backbone via a thermally reversible urethane bond. The urethane linkage between the isocyanate and phenol groups was stable at room temperature, but it cleaved to generate an isocyanate group when the temperature was increased. When annealed, the copolymers in their smectic mesophases became insoluble in common organic solvents, suggesting the formation of network structures. XRD analysis showed that the annealed polymers maintained their smectic LC structures. The crosslinking process probably proceeded via the reaction of the dissociated isocyanate groups. Some of the isocyanate groups would have first reacted with moisture in the atmosphere to yield amino groups, which underwent further reaction with other isocyanate groups, resulting in the formation of urea bonds. We presume that only polymer chains in the same layer were crosslinked by the reaction of the isocyanate groups, resulting in the formation of a layered polymer network structure. Reactions between the layers did not occur because of the wide layer spacing.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1169-1172
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• 2004

Polyimides are blended with photoreactive polymers in order to improve the thermal stability of molecular orientation of photoreactive groups induced by polarized UV irradiation. The polyimide/photopolymer blends can be applied for the photo-induced liquid crystal alignment layers. However, the polyimides are also decomposed by UV irradiation and this may have the negative effect on the orientation of liquid crystals. In order to elucidate the influence of polyimide on the molecular orientation of liquid crystal, non-photoreactive naphthalenic polyimide (1,4,5,8-naphthalene tetracarboxylic dianhydride} was selected for the blend alignment layers. We prepared the blends of photo-reactive coumarin polymers and naphthalenic polyimide, and investigated the orientation of liquid crystals. Thermal stability of the orientation of liquid crystals was enhanced due to the thermally stable polyimide. However, there was no other side-effect of polyimide on the orientation of liquid crystals and this might be attributed to the non-photo-reactivity of naphtahlenic polyimide.

• Journal of Information Display
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• v.5 no.4
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• pp.12-17
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• 2004

A series of statistical random copolymers of dioctylfluorene (DOF) and 3,4-ethylenedioxythiophene (EDOT) were synthesized by Ni (0) mediated polymerization and their light-emitting properties were compared with poly (9,9-di-n-octylfluorene) (PDOF). The synthesized polymers were characterized using UV-vis spectroscopy, TGA, photoluminescence (PL) & electroluminescence (EL) spectroscopy and by conducting molecular weight studies. The resulting polymers were found to be thermally stable and readily soluble in organic solvents. The UV-visible absorption and PL emission spectra of the copolymers were gradually red-shifted as the fraction of EDOT in copolymers increased. Light-emitting devices were fabricated in an ITO (indium-tin oxide)/PEDOT/polymer/Ca/Al configuration. Interestingly, the EL spectra of these devices were similar to the PL spectra of the corresponding polymer film. However, the EL devices constructed from the copolymer showed more than 10 times higher efficiency level than the devices constructed from the PDOF homopolymer. This higher efficiency is possibly the result of better charge carrier balance in the copolymer systems due to the lower HOMO levels of the copolymers in comparison to that of PDOF homopolymer.

• Macromolecular Research
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• v.12 no.2
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• pp.156-171
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• 2004

We describe the precision synthesis schemes of siloxane-containing polymers, i.e., the control of their molecular weight, stereoregularity, and higher-order structures. First, we found a new catalytic dehydrocoupling reaction of water with bis(dimethylsilyl)benzene to give poly(phenylene-disiloxane). Together with this reaction, we applied hetero-condensations to the synthesis of thermally stable poly(arylene-siloxane)s. The dehydrocoupling reaction was applied to the synthesis of syndiotactic poly(methylphenylsiloxane) and poly(silsesquioxane)s, which we also prepared by hydrolysis and deaminative condensation reactions. We discuss the tendency for loop formation to occur in the synthesis of poly(silsesquioxane) by hydrolysis, and provide comments on the design of functionality of the polymers produced. By taking advantage of the low energy barrier to rotation in the silicon-oxygen bond, we designed selective oxygen-permeable membrane materials and liquid crystalline materials. The low surface free energy of siloxane-containing systems allows surface modification of a blend film and the design of holographic grating materials.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2419-2425
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• 2007

New poly(cyclopenta[def]phenanthrene) (PCPP)-based conjugated copolymers, containing carbazole units as pendants, were prepared as the electroluminescent (EL) layer in light-emitting diodes (LEDs) to show that most of them have higher maximum brightness and EL efficiency. The prepared polymers, Poly(2,6-(4-(6-(Ncarbazolyl)- hexyl)-4-octyl-4H-cyclopenta[def]phenanthrene)) (CzPCPP10) and Poly(2,6-(4-(6-(N-carbazolyl)- hexyl)-4-octyl-4H-cyclopenta[def]phenanthrene))-co-(2,6-(4,4-dioctyl-4H-cyclopenta[def]phenanthrene)) (CzPCPP7 and CzPCPP5), were soluble in common organic solvents and used as the EL layer in light-emitting diodes (LEDs) of configuration with ITO/PEDOT/polymer/Ca/Al device. The polymers are thermally stable with glass transition temperature (Tg) at 77-100 °C and decomposition temperature (Td) at 423-457 °C. The studies of cyclic voltammetry indicated same HOME levels in all polymers, although the ratios of carbazole units are different. In case of PLEDs with configuration of ITO/PEDOT/CzPCPPs/Ca/Al device, The EL maximum peaks were around 450 nm, which the turn-on voltages were about 6.0-6.5 V. The maximum luminescence of PLEDs using CzPCPP10 was over 4400 cd/m2 at 6.5 V, which all of the maximum EL efficiency were 0.12 cd/A. The CIE coordinates of the EL spectrum of PLEDs using CzPCPP10 was (0.18, 0.08), which are quite close to that of the standard blue (0.14, 0.08) of NTSC.

• Journal of Hydrogen and New Energy
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• v.28 no.1
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• pp.24-29
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• 2017

A fluorinated polybenzimidazole (FPBI) was synthesized from 3,3-diaminobenzidine (DAB) of tetraamine, 2,2-bis(4-carboxyphenyl)hexafluoropropane of aromatic biscarboxylic acid, and 4,4-sulfonyldibenzoic acid of aromatic biscarboxylic acid in polyphosphoric acid (PPA). A FPBI was easily cast and made into clear films. The structure of condensation polymers and corresponding membranes were analyzed using GPC (gel permeation chromatography), $^1H$-NMR ($^1H$ nuclear magnetic resonance) and FT-IR (fourier transform infrared). TGA (thermogravimetric analysis) analysis showed that the prepared membranes were thermally stable, so that elevated temperature fuel cell operation would be possible. The proton conductivity of the FPBI membranes increased with increasing temperatures in the polymer. A FPBI membrane has a maximum ion conductivity of 45 mS/cm at $90^{\circ}C$ and 100% relative humidity.