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Synthesis and properties of poly(2-ethynylpyridinium bromide) having side-chain liquid crystalline moieties
Optical Materials 21 (2002) 637–641 www.elsevier.com/locate/optmat
Synthesis and properties of poly(2-ethynylpyridinium bromide) having side-chain liquid crystalline moieties T.L. Gui a, S.H. Jin b, J.W. Park c, W.S. Ahn d, K.N. Koh e, S.H. Kim f, Y.S. Gal g,* a
g
Department of Material Physics, Harbin University of Science and Technology, Harbin 150080, China b Department of Chemistry Education, Pusan National University, Pusan 609-735, South Korea c Department of Polymer Engineering, Chungju National University, Chungju 380-702, South Korea d Department of Chemical Engineering, Keimyung University, Daegu 704-701, South Korea e Department of Chemical Engineering, Kyungpook National University, Daegu 702-701, South Korea f Department of Dyeing and Finishing, Kyungpook National University, Daegu 702-701, South Korea Polymer Chemistry Laboratory, College of General Education, Kyungil University, Kyung-buk 712-701, South Korea
Abstract Novel conjugated polymer having side chain liquid crystalline moieties was easily synthesized by the direct polymerization of 2-ethynylpyridine with the corresponding alkyl bromide having a liquid crystalline moiety, 4-{40 -{1000 bromodecyl}oxyphenyl}azobenzoic acid. The polymerization proceeded well to give the resulting polymer in moderate yields. The polymer structure was characterized by various instrumental methods to have conjugated polymer system with liquid crystalline moieties. The photoluminescence spectrum of the polymer film shows that the photoluminescence peak is located at 430 and 454 nm corresponding to the photon energy of 2.80 and 2.66 eV. A needle shape of texture, which is a typical optical texture of smectic phase, was observed. Ó 2002 Elsevier Science B.V. All rights reserved. PACS: 61.30.V Keywords: Conjugated polymers; Polyacetylene; Luminescence; Liquid crystal; 2-Ethynylpyridine
1. Introduction Conjugated polymer systems obtained from acetylene derivatives have been studied as organic semiconductors [1–3], as membranes for gas separation and for liquid-mixture separation [4], as
*
Corresponding author. Tel.: +82-53-850-7115; fax: +82-53850-7600. E-mail address: [email protected] (Y.S. Gal).
materials for enantioseparation for racemates by high performance liquid chromatograpy [5,6], as a side-chain liquid crystal [7–9], as materials for chemical sensors [10], and as materials for nonlinear optical property [11,12] and for photoluminescence and electroluminescence properties [13–17]. Conjugated ionic polymer systems from acetylene derivatives have potential as materials for mixed ionic and electronic conductivity, energy storage devices such as batteries and permselective
0925-3467/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 5 - 3 4 6 7 ( 0 2 ) 0 0 2 1 4 - 8
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membrane, and light-emitting devices, due to the their extensive conjugation and various functionalities [1,18]. The synthesis of simple mono- and di-substituted ionic polyethynylpyridines had been carried out with the activation of the acetylene bond in ethynylpyridines [18,19]. We have studied the polyacetylene materials having pyridine moiety such as poly(2-ethynylpyridine) [20], poly(N-propargylpyridinium bromide) [21], poly(2-ethynyl-Npropargylpyridinium bromide) [22,23], and poly (2-ethynylpyridinium bromide) having a pendant propargyl moiety [17,24,25]. In the present article, we report the studies on the synthesis of a novel conjugated ionic polymer, poly(2-ethynylpyridinium bromide) having the side chain liquid crystalline moiety and the characterization of the resulting conjugated ionic polymer.
2. Experimental The synthesis of conjugated ionic polymer, poly(2-ethynylpyridinium bromide) having the side chain liquid crystalline moiety, was performed as follows. In a 100 ml three-neck flask equipped with a reflux condenser, thermometer, and rubber septum, DMF (20 ml, [M]0 : 0.35 M), 4-{40 -{1000 -bromodecyl}oxyphenyl}azo benzoic acid (4.00 g, 8.66 mmol), and 2-ethynylpyridine (0.894 g, 8.66 mmol) were introduced in the given order. And the reaction was carried out at the elevated temperature of 120 °C. FT-IR spectra were obtained with a Bruker EQUINOX 55 spectrometer using a KBr pellet. NMR (1 H- and 13 C-) spectra were recorded on a Varian 500 MHz FT-NMR spectrometer (model: Unity INOVA) in DMSO-d6 . X-ray diffractograms were obtained with a PHILLIPS X-ray diffractometer (model: XPert-APD). The optical absorption spectra were measured by a Shimadzu UV-3100 UV–VIS–NIR spectrometer. Perkin Elmer luminescence spectrometer LS50 (Xenon flash tube) was used for photoluminescence study. Solid-state emission measurement was achieved using films supported on a quartz substrate and mounted with front-face exitation at an angle of <45°. As sample polymer solution was
cast on a cover glass to form a film and the solvent was dried and removed at RT for 24 h. The film was put in a Mettler FP 82HT hot stage controlled by 0.1 °C. The hot stage was mounted on a Zeiss Jenalab optical microscope. Phase transition and change of texture of the polymer sample were observed with cross-polarizer during heating the sample from RT to 250 °C at a heating rate of 2 °C/min.
3. Results and discussion The direct polymerization of 2-ethynylpyridine activated by alkyl halides is a very facile synthetic method for the conjugated ionic polymer in one step [18,19,22]. The synthesis of poly(2-ethynylpyridinium bromide) having liquid crystalline moieties was performed by the reaction of 2ethynylpyridine and 4-{40 -{1000 -bromodecyl}oxyphenyl}azobenzoic acid without any initiators and catalysts (Scheme 1). The activated acetylenic triple bond of N-alkyl2-ethynylpyridinium halide was known to be susceptible to the polymerization under mild reaction conditions. However, in this polymerization, the polymerization proceeded very slowly below the temperature of 90 °C. Thus the polymerization was performed at the elevated temperature of 120 °C. This polymerization behavior was found to be similar with those of the polymerization reaction of 2-ethynylpyridine with 6-(N-carbazolyl)hexyl bromide [26]. The color of the reaction solution changed from light brown of the initial mixture of 2-EP and LC moiety into dark black. The polymer yield calculated from the precipitation according
Scheme 1. Synthesis of poly(2-ethynylpyridinium bromide) with LC Moieties.
T.L. Gui et al. / Optical Materials 21 (2002) 637–641
to the polymerization time revealed that this polymerization proceeded gradually upto 24 h. The maximum polymer yield was 53%. The solvent effect for the polymerization were also tested. The polymerizations were found to proceed well in the polar solvents such as DMF, NMP, DMSO etc. to give moderate yields of polymers (45–53%). This polymerization was influenced strongly upon the initial monomer concentration ([M]0 ). As the initial monomer concentration was increased, the polymer yield and molecular weight were also increased. The polymers were obtained in powder form regardless of the solvents used. The polymer structure of poly(2-ethynylpyridinium bromide) having liquid crystalline moieties was characterized by 1 H-NMR, infrared, and UV– visible spectroscopies. The FT-IR spectrum of the polymer did not show the acetylenic CBC bond stretching (2110 cm1 ) and acetylenic CAH bond stretching (3293 cm1 ) frequencies. Instead, the C@C stretching frequency peak of conjugated polymer backbone at 1620 cm1 became more intense than those C@C and C@N stretching frequency of 2-EP and LC moieties. In general, the NMR spectrum of conjugated polymers having pyridyl moieties showed a poor quality because of the line-broadening effect of ionic pyridyl moieties. The 1 H-NMR spectrum of the polymer showed the
639
aromatic proton peaks at 6.5–9.5 ppm. The vinyl proton of the conjugated polymer backbone was also observed broadly at the aromatic region in the range of 6.5–7.0 ppm. The peaks of methylene protons were observed in the range of 1.2–1.8 ppm and 3.1–3.6 ppm. As mentioned previously, the UV–visible spectrum of the polymer showed a characteristic peaks at the visible region, which is a characteristic peak of a conjugated polymer system. These spectral data indicated that the polymer have a conjugated backbone system having liquid crystalline moieties. The resulting polymers were generally black and were completely soluble in DMF, DMSO, N,N-dimethylacetamide, formic acid, etc. The inherent viscosities of the resulting polymers were in the range of 0.10–0.14 dL/g, depending on the polymerization conditions. The morphology of the polymer was also investigated by X-ray diffraction analysis. Because the peak in the diffraction pattern was broad and the ratio of the half-height width to diffraction angle (D2h/2h) is greater than 0.35 [27], the polymer was amorphous. Fig. 1 shows the optical absorption and photoluminescence spectra of this film (thickness 1 lm) on quartz substrate. The absorption spectrum starts around 550 nm, and shows a strong absorption band at around 357 and 370 nm due to the p ! p* interband transition
Fig. 1. Optical absorption and photoluminescence spectra of the polymer film (thickness 1 lm).
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Fig. 2. Cross-polarized optical micrograph of the polymer sample at 150 °C.
of a pyridinium moiety. The photoluminescence spectrum of the film shows that the photoluminescence peak is located at 430 and 454 nm corresponding to the photon energy of 2.8 and 2.66 eV. The temperature-dependent photoluminescence spectra of the polymer film were measured. As the temperature was increased, the photoluminescence intensity decreased. This is because the nonradiative decay channels were increased as the temperature increased. But there were no changes in the location of the peak and the line shape of the spectrum as the temperature was varied. Thus the temperature did not affect exciton states of this conjugated polymer. A needle shape of texture, which is a typical optical texture of smectic phase, is shown in Fig. 2. This texture was maintained up to 190 °C during heating the sample with rate of 2 °C/min, showing the isotropic transition at 190 °C. When the sample, however, was cooled from 250 °C to RT, considerable portion of LC texture disappeared. This fact seemed due to the thermal cross-linking of the sample at higher temperature above 200 °C.
4. Conclusions New conjugated ionic polymer was prepared by the direct polymerization of 2-ethynylpyridine and 4-{40 -{1000 -bromodecyl}oxyphenyl}azobenzoic acid without any initiator and catalysts. This polymerization gave a soluble and easily processible
ionic conjugated polymer in moderate yields. The polymer structure was characterized by various instrumental methods to have a conjugated polymer backbone system having liquid crystalline moieties. The polymers were soluble in polar organic solvents such as DMF, DMSO, N, N-dimethylacetamide, and well processible into a homogeneous thin film. The photoluminescence spectrum of the film shows that the photoluminescence peak is located at 430 and 454 nm corresponding to the photon energy of 2.8 and 2.66 eV. As the temperature was increased, the photoluminescence intensity decreased. A needle shape of texture, which is a typical liquid crystal texture of smectic phase, was observed.
Acknowledgement This work was supported by grant no. 2000-230800-001-3 from the Basic Research Program of the Korea Science and Engineering Foundation (KOSEF).
References [1] Y.S. Gal, S.K. Choi, J. Appl. Polym. Sci. 50 (1993) 601. [2] S.K. Choi, Y.S. Gal, S.H. Jin, H.K. Kim, Chem. Rev. 100 (2000) 1645. [3] M. Leclerc, Angew. Chem. Int. Ed. 40 (2001) 2581. [4] T. Okubo, S. Kohmoto, M. Yamamoto, K. Yamada, J. Polym. Sci.: Part A: Polym. Chem. 36 (1998) 603. [5] E. Yashimura, T. Matsushima, T. Nimura, Y. Okamoto, Korea Polym. J. 4 (1996) 139. [6] T. Aoki, K.I. Shinohara, T. Kaneko, E. Oikawa, Macromolecules 29 (1996) 4192. [7] S.H. Jin, S.H. Kim, H.N. Cho, S.K. Choi, Macromolecules 24 (1991) 6050. [8] S.K. Choi, J.H. Lee, S.J. Kang, S.H. Jin, Prog. Polym. Sci. 22 (1997) 693. [9] P. Stagnaro, B. Cavazza, V. Trefiletti, G. Costa, B. Gallot, B. Valenti, Macromol. Chem. Phys. 202 (2001) 2065. [10] L.S. Hwang, J.M. Ko, H.W. Rhee, C.Y. Kim, Synth. Met. 55–57 (1993) 3671. [11] C. Halvorson, A. Hays, B. Kraabel, R. Wu, F. Wudl, A.J. Heeger, Science 265 (1994) 1215. [12] K. Shiga, T. Inoguchi, K. Mori, K. Kondo, K. Kamada, K. Tawa, K. Ohta, T. Maruo, E. Mochizuki, Y. Kai, Macromol. Chem. Phys. 202 (2001) 257. [13] K. Tada, R. Hidayat, M. Teraguchi, T. Masuda, K. Yoshino, Jpn. J. Appl. Phys. 35 (1996) L1138.
T.L. Gui et al. / Optical Materials 21 (2002) 637–641 [14] Y.S. Gal, W.C. Lee, S.J. Lee, J.W. Park, J.M. Ko, J.H. Chun, J. Macromol. Sci.-Pure Appl. Chem. A 36 (1999) 1503. [15] U.H. Bunz, Chem. Rev. 100 (2000) 1605. [16] Y.S. Gal, W.C. Lee, S.S. Lee, J.S. Bae, B.S. Kim, S.H. Jang, S.H. Jin, J.W. Park, Korea Polym. J. 8 (2000) 131. [17] Y.S. Gal, W.C. Lee, S.Y. Kim, J.W. Park, S.H. Jin, K.N. Koh, S.H. Kim, J. Polym. Sci.: Part A: Polym. Chem. 39 (2001) 3151. [18] A. Blumstein, S. Subramanyam, US Patent 5,037,916, Aug. 6, 1991. [19] S. Subramanyam, A. Blumstein, Macromolecules 24 (1991) 2668. [20] Y.S. Gal, H.N. Cho, S.K. Kwon, S.K. Choi, Polymer (Korea) 12 (1988) 30.
641
[21] Y.S. Gal, B. Jung, W.C. Lee, S.K. Choi, Bull. Korean Chem. Soc. 15 (1994) 267. [22] Y.S. Gal, W.C. Lee, J.H. Lee, S.K. Choi, Bull. Korean Chem. Soc. 19 (1998) 22. [23] Y.S. Gal, W.C. Lee, T.L. Gui, S.S. Lee, J.S. Bae, B.S. Kim, S.H. Jang, S.H. Jin, Bull. Korean Chem. Soc. 22 (2001) 183. [24] Y.S. Gal, W.C. Lee, S.K. Choi, Bull. Korean Chem. Soc. 18 (1997) 265. [25] C.Y. Lee, H.M. Kim, J.W. Park, Y.S. Gal, J.I. Jin, J. Joo, Synth. Met. 117 (2001) 109. [26] Y.S. Gal, S.S. Lee, J.S. Bae, B.S. Kim, S.H. Jang, S.H. Jin, Bull. Korean Chem. Soc. 20 (1999) 451. [27] T. Masuda, T. Higashimura, Acc. Chem. Res. 17 (1981) 51.
Synthesis and properties of poly(2-ethynylpyridinium bromide) having side-chain liquid crystalline moieties T.L. Gui a, S.H. Jin b, J.W. Park c, W.S. Ahn d, K.N. Koh e, S.H. Kim f, Y.S. Gal g,* a
g
Department of Material Physics, Harbin University of Science and Technology, Harbin 150080, China b Department of Chemistry Education, Pusan National University, Pusan 609-735, South Korea c Department of Polymer Engineering, Chungju National University, Chungju 380-702, South Korea d Department of Chemical Engineering, Keimyung University, Daegu 704-701, South Korea e Department of Chemical Engineering, Kyungpook National University, Daegu 702-701, South Korea f Department of Dyeing and Finishing, Kyungpook National University, Daegu 702-701, South Korea Polymer Chemistry Laboratory, College of General Education, Kyungil University, Kyung-buk 712-701, South Korea
Abstract Novel conjugated polymer having side chain liquid crystalline moieties was easily synthesized by the direct polymerization of 2-ethynylpyridine with the corresponding alkyl bromide having a liquid crystalline moiety, 4-{40 -{1000 bromodecyl}oxyphenyl}azobenzoic acid. The polymerization proceeded well to give the resulting polymer in moderate yields. The polymer structure was characterized by various instrumental methods to have conjugated polymer system with liquid crystalline moieties. The photoluminescence spectrum of the polymer film shows that the photoluminescence peak is located at 430 and 454 nm corresponding to the photon energy of 2.80 and 2.66 eV. A needle shape of texture, which is a typical optical texture of smectic phase, was observed. Ó 2002 Elsevier Science B.V. All rights reserved. PACS: 61.30.V Keywords: Conjugated polymers; Polyacetylene; Luminescence; Liquid crystal; 2-Ethynylpyridine
1. Introduction Conjugated polymer systems obtained from acetylene derivatives have been studied as organic semiconductors [1–3], as membranes for gas separation and for liquid-mixture separation [4], as
*
Corresponding author. Tel.: +82-53-850-7115; fax: +82-53850-7600. E-mail address: [email protected] (Y.S. Gal).
materials for enantioseparation for racemates by high performance liquid chromatograpy [5,6], as a side-chain liquid crystal [7–9], as materials for chemical sensors [10], and as materials for nonlinear optical property [11,12] and for photoluminescence and electroluminescence properties [13–17]. Conjugated ionic polymer systems from acetylene derivatives have potential as materials for mixed ionic and electronic conductivity, energy storage devices such as batteries and permselective
0925-3467/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 5 - 3 4 6 7 ( 0 2 ) 0 0 2 1 4 - 8
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T.L. Gui et al. / Optical Materials 21 (2002) 637–641
membrane, and light-emitting devices, due to the their extensive conjugation and various functionalities [1,18]. The synthesis of simple mono- and di-substituted ionic polyethynylpyridines had been carried out with the activation of the acetylene bond in ethynylpyridines [18,19]. We have studied the polyacetylene materials having pyridine moiety such as poly(2-ethynylpyridine) [20], poly(N-propargylpyridinium bromide) [21], poly(2-ethynyl-Npropargylpyridinium bromide) [22,23], and poly (2-ethynylpyridinium bromide) having a pendant propargyl moiety [17,24,25]. In the present article, we report the studies on the synthesis of a novel conjugated ionic polymer, poly(2-ethynylpyridinium bromide) having the side chain liquid crystalline moiety and the characterization of the resulting conjugated ionic polymer.
2. Experimental The synthesis of conjugated ionic polymer, poly(2-ethynylpyridinium bromide) having the side chain liquid crystalline moiety, was performed as follows. In a 100 ml three-neck flask equipped with a reflux condenser, thermometer, and rubber septum, DMF (20 ml, [M]0 : 0.35 M), 4-{40 -{1000 -bromodecyl}oxyphenyl}azo benzoic acid (4.00 g, 8.66 mmol), and 2-ethynylpyridine (0.894 g, 8.66 mmol) were introduced in the given order. And the reaction was carried out at the elevated temperature of 120 °C. FT-IR spectra were obtained with a Bruker EQUINOX 55 spectrometer using a KBr pellet. NMR (1 H- and 13 C-) spectra were recorded on a Varian 500 MHz FT-NMR spectrometer (model: Unity INOVA) in DMSO-d6 . X-ray diffractograms were obtained with a PHILLIPS X-ray diffractometer (model: XPert-APD). The optical absorption spectra were measured by a Shimadzu UV-3100 UV–VIS–NIR spectrometer. Perkin Elmer luminescence spectrometer LS50 (Xenon flash tube) was used for photoluminescence study. Solid-state emission measurement was achieved using films supported on a quartz substrate and mounted with front-face exitation at an angle of <45°. As sample polymer solution was
cast on a cover glass to form a film and the solvent was dried and removed at RT for 24 h. The film was put in a Mettler FP 82HT hot stage controlled by 0.1 °C. The hot stage was mounted on a Zeiss Jenalab optical microscope. Phase transition and change of texture of the polymer sample were observed with cross-polarizer during heating the sample from RT to 250 °C at a heating rate of 2 °C/min.
3. Results and discussion The direct polymerization of 2-ethynylpyridine activated by alkyl halides is a very facile synthetic method for the conjugated ionic polymer in one step [18,19,22]. The synthesis of poly(2-ethynylpyridinium bromide) having liquid crystalline moieties was performed by the reaction of 2ethynylpyridine and 4-{40 -{1000 -bromodecyl}oxyphenyl}azobenzoic acid without any initiators and catalysts (Scheme 1). The activated acetylenic triple bond of N-alkyl2-ethynylpyridinium halide was known to be susceptible to the polymerization under mild reaction conditions. However, in this polymerization, the polymerization proceeded very slowly below the temperature of 90 °C. Thus the polymerization was performed at the elevated temperature of 120 °C. This polymerization behavior was found to be similar with those of the polymerization reaction of 2-ethynylpyridine with 6-(N-carbazolyl)hexyl bromide [26]. The color of the reaction solution changed from light brown of the initial mixture of 2-EP and LC moiety into dark black. The polymer yield calculated from the precipitation according
Scheme 1. Synthesis of poly(2-ethynylpyridinium bromide) with LC Moieties.
T.L. Gui et al. / Optical Materials 21 (2002) 637–641
to the polymerization time revealed that this polymerization proceeded gradually upto 24 h. The maximum polymer yield was 53%. The solvent effect for the polymerization were also tested. The polymerizations were found to proceed well in the polar solvents such as DMF, NMP, DMSO etc. to give moderate yields of polymers (45–53%). This polymerization was influenced strongly upon the initial monomer concentration ([M]0 ). As the initial monomer concentration was increased, the polymer yield and molecular weight were also increased. The polymers were obtained in powder form regardless of the solvents used. The polymer structure of poly(2-ethynylpyridinium bromide) having liquid crystalline moieties was characterized by 1 H-NMR, infrared, and UV– visible spectroscopies. The FT-IR spectrum of the polymer did not show the acetylenic CBC bond stretching (2110 cm1 ) and acetylenic CAH bond stretching (3293 cm1 ) frequencies. Instead, the C@C stretching frequency peak of conjugated polymer backbone at 1620 cm1 became more intense than those C@C and C@N stretching frequency of 2-EP and LC moieties. In general, the NMR spectrum of conjugated polymers having pyridyl moieties showed a poor quality because of the line-broadening effect of ionic pyridyl moieties. The 1 H-NMR spectrum of the polymer showed the
639
aromatic proton peaks at 6.5–9.5 ppm. The vinyl proton of the conjugated polymer backbone was also observed broadly at the aromatic region in the range of 6.5–7.0 ppm. The peaks of methylene protons were observed in the range of 1.2–1.8 ppm and 3.1–3.6 ppm. As mentioned previously, the UV–visible spectrum of the polymer showed a characteristic peaks at the visible region, which is a characteristic peak of a conjugated polymer system. These spectral data indicated that the polymer have a conjugated backbone system having liquid crystalline moieties. The resulting polymers were generally black and were completely soluble in DMF, DMSO, N,N-dimethylacetamide, formic acid, etc. The inherent viscosities of the resulting polymers were in the range of 0.10–0.14 dL/g, depending on the polymerization conditions. The morphology of the polymer was also investigated by X-ray diffraction analysis. Because the peak in the diffraction pattern was broad and the ratio of the half-height width to diffraction angle (D2h/2h) is greater than 0.35 [27], the polymer was amorphous. Fig. 1 shows the optical absorption and photoluminescence spectra of this film (thickness 1 lm) on quartz substrate. The absorption spectrum starts around 550 nm, and shows a strong absorption band at around 357 and 370 nm due to the p ! p* interband transition
Fig. 1. Optical absorption and photoluminescence spectra of the polymer film (thickness 1 lm).
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T.L. Gui et al. / Optical Materials 21 (2002) 637–641
Fig. 2. Cross-polarized optical micrograph of the polymer sample at 150 °C.
of a pyridinium moiety. The photoluminescence spectrum of the film shows that the photoluminescence peak is located at 430 and 454 nm corresponding to the photon energy of 2.8 and 2.66 eV. The temperature-dependent photoluminescence spectra of the polymer film were measured. As the temperature was increased, the photoluminescence intensity decreased. This is because the nonradiative decay channels were increased as the temperature increased. But there were no changes in the location of the peak and the line shape of the spectrum as the temperature was varied. Thus the temperature did not affect exciton states of this conjugated polymer. A needle shape of texture, which is a typical optical texture of smectic phase, is shown in Fig. 2. This texture was maintained up to 190 °C during heating the sample with rate of 2 °C/min, showing the isotropic transition at 190 °C. When the sample, however, was cooled from 250 °C to RT, considerable portion of LC texture disappeared. This fact seemed due to the thermal cross-linking of the sample at higher temperature above 200 °C.
4. Conclusions New conjugated ionic polymer was prepared by the direct polymerization of 2-ethynylpyridine and 4-{40 -{1000 -bromodecyl}oxyphenyl}azobenzoic acid without any initiator and catalysts. This polymerization gave a soluble and easily processible
ionic conjugated polymer in moderate yields. The polymer structure was characterized by various instrumental methods to have a conjugated polymer backbone system having liquid crystalline moieties. The polymers were soluble in polar organic solvents such as DMF, DMSO, N, N-dimethylacetamide, and well processible into a homogeneous thin film. The photoluminescence spectrum of the film shows that the photoluminescence peak is located at 430 and 454 nm corresponding to the photon energy of 2.8 and 2.66 eV. As the temperature was increased, the photoluminescence intensity decreased. A needle shape of texture, which is a typical liquid crystal texture of smectic phase, was observed.
Acknowledgement This work was supported by grant no. 2000-230800-001-3 from the Basic Research Program of the Korea Science and Engineering Foundation (KOSEF).
References [1] Y.S. Gal, S.K. Choi, J. Appl. Polym. Sci. 50 (1993) 601. [2] S.K. Choi, Y.S. Gal, S.H. Jin, H.K. Kim, Chem. Rev. 100 (2000) 1645. [3] M. Leclerc, Angew. Chem. Int. Ed. 40 (2001) 2581. [4] T. Okubo, S. Kohmoto, M. Yamamoto, K. Yamada, J. Polym. Sci.: Part A: Polym. Chem. 36 (1998) 603. [5] E. Yashimura, T. Matsushima, T. Nimura, Y. Okamoto, Korea Polym. J. 4 (1996) 139. [6] T. Aoki, K.I. Shinohara, T. Kaneko, E. Oikawa, Macromolecules 29 (1996) 4192. [7] S.H. Jin, S.H. Kim, H.N. Cho, S.K. Choi, Macromolecules 24 (1991) 6050. [8] S.K. Choi, J.H. Lee, S.J. Kang, S.H. Jin, Prog. Polym. Sci. 22 (1997) 693. [9] P. Stagnaro, B. Cavazza, V. Trefiletti, G. Costa, B. Gallot, B. Valenti, Macromol. Chem. Phys. 202 (2001) 2065. [10] L.S. Hwang, J.M. Ko, H.W. Rhee, C.Y. Kim, Synth. Met. 55–57 (1993) 3671. [11] C. Halvorson, A. Hays, B. Kraabel, R. Wu, F. Wudl, A.J. Heeger, Science 265 (1994) 1215. [12] K. Shiga, T. Inoguchi, K. Mori, K. Kondo, K. Kamada, K. Tawa, K. Ohta, T. Maruo, E. Mochizuki, Y. Kai, Macromol. Chem. Phys. 202 (2001) 257. [13] K. Tada, R. Hidayat, M. Teraguchi, T. Masuda, K. Yoshino, Jpn. J. Appl. Phys. 35 (1996) L1138.
T.L. Gui et al. / Optical Materials 21 (2002) 637–641 [14] Y.S. Gal, W.C. Lee, S.J. Lee, J.W. Park, J.M. Ko, J.H. Chun, J. Macromol. Sci.-Pure Appl. Chem. A 36 (1999) 1503. [15] U.H. Bunz, Chem. Rev. 100 (2000) 1605. [16] Y.S. Gal, W.C. Lee, S.S. Lee, J.S. Bae, B.S. Kim, S.H. Jang, S.H. Jin, J.W. Park, Korea Polym. J. 8 (2000) 131. [17] Y.S. Gal, W.C. Lee, S.Y. Kim, J.W. Park, S.H. Jin, K.N. Koh, S.H. Kim, J. Polym. Sci.: Part A: Polym. Chem. 39 (2001) 3151. [18] A. Blumstein, S. Subramanyam, US Patent 5,037,916, Aug. 6, 1991. [19] S. Subramanyam, A. Blumstein, Macromolecules 24 (1991) 2668. [20] Y.S. Gal, H.N. Cho, S.K. Kwon, S.K. Choi, Polymer (Korea) 12 (1988) 30.
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[21] Y.S. Gal, B. Jung, W.C. Lee, S.K. Choi, Bull. Korean Chem. Soc. 15 (1994) 267. [22] Y.S. Gal, W.C. Lee, J.H. Lee, S.K. Choi, Bull. Korean Chem. Soc. 19 (1998) 22. [23] Y.S. Gal, W.C. Lee, T.L. Gui, S.S. Lee, J.S. Bae, B.S. Kim, S.H. Jang, S.H. Jin, Bull. Korean Chem. Soc. 22 (2001) 183. [24] Y.S. Gal, W.C. Lee, S.K. Choi, Bull. Korean Chem. Soc. 18 (1997) 265. [25] C.Y. Lee, H.M. Kim, J.W. Park, Y.S. Gal, J.I. Jin, J. Joo, Synth. Met. 117 (2001) 109. [26] Y.S. Gal, S.S. Lee, J.S. Bae, B.S. Kim, S.H. Jang, S.H. Jin, Bull. Korean Chem. Soc. 20 (1999) 451. [27] T. Masuda, T. Higashimura, Acc. Chem. Res. 17 (1981) 51.