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A crystalline cyclic (aryl ether ketone) oligomer containing tetramethylbiphenylene moiety
PERGAMON
European Polymer Journal 35 (1999) 1967±1974
A crystalline cyclic (aryl ether ketone) oligomer containing tetramethylbiphenylene moiety M. Shibata a, *, R. Yosomiya a, C. Chen b, H. Zhou b, J. Wang b, Z. Wu b a
Department of Industrial Chemistry, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan b Department of Chemistry, Jilin University, Changchun 130023, People's Republic of China Received 2 September 1998; accepted 6 November 1998
Abstract A highly methyl-substituted cyclic (aryl ether ketone) oligomer was successfully synthesized by the reaction of 3,3 0 ,5,5 0 -tetramethyl-4,4 0 -biphenol (TMBPH) and 4,4 0 -di¯uorobenzophenone with the use of a pseudo- high dilution condition. The structure of the cyclic oligomer was characterized by IR, NMR, matrix-assisted laser desorption ionization time-of-¯ight mass spectroscopy and gel permeation chromatography analyses. From the measurement of wide angle X- ray diraction it was revealed that the cyclic oligomer is crystalline, in contrast to the fact that the corresponding linear polymer is amorphous. The dierence in the crystallization behavior is discussed based on molecular modeling. # 1999 Elsevier Science Ltd. All rights reserved.
1. Introduction The use of macrocyclic oligomers as intermediates for the synthesis of high-performance engineering polymers has been rapidly extended to several systems such as cyclic esters [1, 2], amide [1, 3], ether imides [1], and ether ketones [4±12], since the pioneering work of Brunelle and Shannon on macrocyclic carbonates [13]. In our previous paper on the synthesis and properties of a new cyclic (aryl ether ketone) oligomer (CBAEK) derived from 4,4 0 -di¯uorobenzophenone and bisphenol A, it was revealed that CBAEK possessing an isopropylidene group in the main chain is crystalline in contrast to the fact that the corresponding linear oligomer and polymer are amorphous [14]. The crystallinity of
* Corresponding author. Tel.: 0474-78-0423; fax: 0474-780439; e-mail: [email protected]
the highly methyl-substituted cyclic (aryl ether ketone)s is an interesting problem in relation to the former results. The present paper concerns the synthesis and crystallinity of a tetramethylbiphenol-based cyclic (aryl ether ketone) (CMAEK).
2. Experimental 2.1. Materials All the materials were used as provided. 4,4 0 Di¯uorobenzophenone (m.p. 103±1048C) was received from Yanbian Longjing Chemical Factory. 3,3 0 ,5,5 0 Tetramethyl-4,4 0 -biphenol (TMBPH) was provided by Mitsubishi Chemical Co. Ltd. Toluene, N,N- dimethylformamide (DMF) and potassium carbonate were provided by Aldrich.
0014-3057/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S 0 0 1 4 - 3 0 5 7 ( 9 8 ) 0 0 2 9 2 - 4
1968
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
2.2. Synthesis of CMAEK
To a 1 l three-neck round-bottom ¯ask, which was equipped with a Dean-Stark trap, mechanical stirring, and nitrogen inlet and outlet, were added 500 ml DMF, 30 ml toluene and potassium carbonate (4.15 g, 30.0 mmol). The mixture was heated to re¯ux. The temperature range of the re¯uxing solution was 145± 1488C. A solution of 4,4 0 - di¯uorobenzophenone (5.46 g, 25.0 mmol) and 3,3 0 ,5,5 0 -tetramethyl-4,4 0 biphenol (6.06 g, 25.0 mmol) in 40 ml DMF was added
over an 8 h period via a syringe pump. After the addition was completed, the resulting solution was re¯uxed for another 8 h. The reaction mixture was cooled and ®ltered to remove salts. The ®ltrate was concentrated in vacuo and cooled to room temperature. The obtained precipitate was ®ltered and repeatedly washed with acetone and water (for a total of 10 times), and ®nally dried in vacuo at 1408C for 24 h. The yield of CMAEK was 9.6 g (91% yield).
Fig. 1. IR spectrum of CMAEK.
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
Fig. 2.
19
F-NMR spectra of (a) PMAEK and (b) CMAEK in CDCl3 containing CF3CO2H.
Fig. 3. 1H-NMR spectrum of CMAEK in CDCl3.
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M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
salts. The ®ltrate was concentrated in vacuo and poured into water to precipitate the product. The precipitate was ®ltered and repeatedly washed with acetone and water (for a total of 10 times), and ®nally dried in vacuo at 1408C for 24 h. The yield of PMAEK was 34.7 g (89% yield). 2.4. Measurements IR spectra were measured on a Nicolet 5DX-FTIR spectrometer (KBr method). Wide-angle X-ray diraction (WAXD) was measured on a Shimazu XD-3A Xray diractometer with a scanning rate of 48 min ÿ 1, using CuKa radiation, at 30 kV and 20 mA. Gel permeation chromatography (GPC) analysis was performed on a Shimazu LC-9A instrument equipped with linear two PLgel 5 mm Mixed-D columns (Polymer Laboratories Ltd), using tetrahydrofuran as eluent at pressure 32 kg cm ÿ 2, elution rate 0.5 ml min ÿ 1 and an RI detector. Matrix-assisted laser desorption ionization time-of¯ight mass spectroscopy (MALDI-TOF-MS) analysis was performed on an LDI 1700-TOF-MS (Biomolecular USA). NMR spectra were recorded on a Varian Unity-400 instrument (400 MHz) at 258C, using CDCl3 as solvent. Modeling of the molecular structure based on the MM2 method was performed using Chem3D version 3.1.1 (Cambridge Scienti®c Computing, Inc.). 3. Results and discussion 3.1. Characterization of CMAEK
Fig. 4. 1H-1H DQCOSY NMR spectra of CMAEK in CDCl3.
2.3. Synthesis of the corresponding ¯uorine-terminated linear polymer (PMAEK) To a 1 l three-neck round-bottom ¯ask, which was equipped with a Dean-Stark trap, mechanical stirring, and nitrogen inlet and outlet, were added 4,4 0 -di¯uorobenzophenone (21.8 g, 100 mmol), 3,3 0 ,5,5 0 -tetramethyl- 4,4 0 -biphenol (20.6 g, 85.0 mmol), potassium carbonate (13.8 g, 100 mmol), and 320 ml DMF and 240 ml toluene. The mixture was kept at re¯ux for 6 h. The reaction mixture was cooled and ®ltered to remove
Fig. 1 shows the IR spectrum of CMAEK. No absorption due to a hydroxyl group at around 3400 cm ÿ 1 is observed, indicating that the cyclic oligomer possesses no appreciable terminal hydroxyl group. Fig. 2 shows the 19F-NMR spectra of CMAEK and PMAEK. A signal of terminal ¯uorine atom for PMAEK appeared at ÿ32 ppm relative to the F-signal of tri¯uoroacetic acid used for an internal standard. No appreciable F-signal appeared around ÿ32 ppm in the 19 F-NMR spectrum of CMAEK, indicating the absence of terminal ¯uorine atom. These results suggest that CMAEK has cyclic structure. Figs. 3 and 4 show 1H-NMR and 1H-1H DQCOSY NMR spectra of CMAEK in CDCl3, respectively. The 1 H- signals around 7.7±7.8 ppm and 6.8±6.9 ppm are assigned to Ha and Hb of CMAEK because they are coupled each other. Also, the 1H-signals around 7.2± 7.4 ppm are assigned to Hc because they are coupled with 1H-signals of methyl groups appeared around 2.1±2.2 ppm. Fig. 5(a) and (b) shows 13C-NMR spectra of CMAEK and PMAEK in CDCl3, respectively.
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
Fig. 5. 13C-NMR spectra of (a) PMAEK and (b) CMAEK in CDCl3. (CMAEK: the magni®ed. Therefore, the signal intensity of each carbon cannot be directly compared.
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C-signals for each carbon are arbitrarily
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M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
Fig. 6. MALDI-TOF-MS spectrum of CMAEK.
Ten kinds of carbons in the repeating unit of PMAEK are assigned as follows: C1 161.1, C2 114.2, C3 132.3, C4 131.3, C5 194.1, C6 150.0, C7 131.3, C8 127.7, C9 137.8, C10 16.3 ppm. On the other hand, all the signals of C1±10 for CMAEK were split in a complicated pattern. This result indicates that the dierence of ring size of the macrocycle aects the chemical shift of each carbon, and CMAEK consists of many macrocycles with dierent ring size.
macrocycles together with sodium adducts [Mn + Na] + of the desired macrocycles, up to pentameter (n = 5), with reasonable signal to noise ratio (Fig. 6 and Table 1). The GPC chart of CMAEK is shown in Fig. 7, which indicates along with MALDITOF-MS data that the smallest ring (dimer) is the most easily formed.
3.2. Molecular weight distribution of CMAEK
The WAXD spectrum of CMAEK suggests that the cyclic oligomer is crystalline (Fig. 8). On the contrary, no crystalline peak was observed for the corresponding linear polymer (PMAEK). A similar tendency was observed for the previously reported bisphenol A-
3.3. Solid structures of CMAEK
The MALDI-TOF-MS spectrum of CMAEK, using 2,5-dihydroxybenzoic acid as the matrix material, gives the correct molecular ion peaks [Mn] + for the desired Table 1 MALDI-TOF-MS data of CMAEK Signal (m/e)
Relative intensity (%)
Assignmenta
Calculated m/e
Deviationb
841.3 1261.2 1684.0 2104.0
100 50 30 20
M2 M3 M4 M5
841.0 1261.5 1682.0 2102.5
+ 0.3 ÿ0.3 + 2.0 + 1.5
a Mx represents the molecular ion with x repeating units; the average molecular weights calculated for repeating unit C29H24O3 = 420.5. b Deviation = (experimental value)-(calculated value).
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
1973
Fig. 7. GPC trace of CMAEK.
based cyclic (aryl ether ketone) (CBAEK) and the corresponding linear oligomers. Considering that these cyclic and linear compounds have the highly methylsubstituted structure, it is interesting that only the cyclic oligomer is crystalline. Modeling based on MM2 method for both cyclic and linear dimers was performed in order to clarify a factor of the crystallization of the highly methyl-substituted macrocycle. As shown in Fig. 9, tetramethylbiphenol-based cyclic (aryl ether ketone) dimer (CMAEK (n = 2)) and its unsubstituted derivative had a similar conformation regardless of the methyl substitution. In contrast to this result, the conformation of tetramethylbiphenol-based linear (aryl ether ketone) dimer (PMAEK (n = 2)) was highly deviated from that of its unsubstituted linear dimer
Fig. 8. WAXD pattern of CMAEK.
(Fig. 10). The terminal benzophenone moiety and tetramethylbiphenylene moiety of PMAEK (n = 2)) are very far apart because of the steric hindrance, as compared with its unsubstituted derivative. Although we cannot discuss the strict conformational change because the molecular structure is not an energy-optimized structure, it is apparent that the conformational change of the linear oligomer by the methyl substitution is much larger than that of the cyclic one. The
Fig. 9. Molecular structure of (a) CMAEK (n = 2) and (b) its unsubstituted derivative calculated by MM2 method.
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M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
Fig. 10. Molecular structure of (a) PMAEK (n = 2) and (b) its unsubstituted derivative calculated by MM2 method.
rigid and symmetrical conformation for the cyclic oligomers regardless of the methyl substitution is thought to be related to their crystallization. X-ray single crystal analyses of these oligomers are now under investigation in order to clarify this reasoning.
4. Conclusions A cyclic (aryl ether ketone) oligomer containing tetramethylbiphenylene moiety was synthesized by the reaction of 3,3 0 ,5,5 0 -tetramethylbiphenol and 4,4 0 di¯uorobenzophenone with the use of pseudo-high dilution condition. From the measurement of wide angle X-ray diraction it was revealed that the cyclic oligomer is crystalline in contrast to the fact that the corresponding linear polymer is amorphous. From the consideration by the modeling based on MM2 method, it was expected that the crystallization of the cyclic oligomer is attributed to its rigid and symmetrical conformation as compared with the corresponding linear oligomer.
References [1] Guggenheim TL, McCormick SJ, Kelly JJ, Brunelle DJ, Colley AM, Boden EP, Shannon TG. Polym Prepr (Am Chem Soc, Div Polym Chem) 1989;30(2):579. [2] Hodge P, Houghton MP, Lee MSK. J Chem Soc, Chem Commun 1993;6:581. [3] Memeger W, Jr, Lazar J, Ovenall D, Leach RA. Macromolecules 1993;26:3476. [4] Wang Y-F, Chan Kwok P, Hay AS. J Polym Sci, Part A: Polym Chem 1996;34:374. [5] Chan Kwok P, Wang Y-F, Hay AS. Macromolecules 1995;28:6705. [6] Chan Kwok P, Wang Y-F, Hay AS. Macromolecules 1995;28:653. [7] Gao C, Hay AS. Polymer 1995;36:4141. [8] Chen M-F, Gibson HW. Macromolecules 1996;29:5502. [9] Chen M-F, Fronczek F, Gibson HW. Macromol Chem Phys 1996;197:4069. [10] Teasley MF, Hsiao BS. Macromolecules 1996;29:6432. [11] Ding Y, Hay AS. Macromolecules 1996;20:3090. [12] Jiang H, Chen T, Qi Y, Xu J. Polymer J. 1998;30:300. [13] Brunelle DJ, Shannon TG. Macromolecules 1991;24:3035. [14] Shibata M, Yosomiya R, Chen C, Wang J, Wu Z. Angew Makromol Chem, in press.
European Polymer Journal 35 (1999) 1967±1974
A crystalline cyclic (aryl ether ketone) oligomer containing tetramethylbiphenylene moiety M. Shibata a, *, R. Yosomiya a, C. Chen b, H. Zhou b, J. Wang b, Z. Wu b a
Department of Industrial Chemistry, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan b Department of Chemistry, Jilin University, Changchun 130023, People's Republic of China Received 2 September 1998; accepted 6 November 1998
Abstract A highly methyl-substituted cyclic (aryl ether ketone) oligomer was successfully synthesized by the reaction of 3,3 0 ,5,5 0 -tetramethyl-4,4 0 -biphenol (TMBPH) and 4,4 0 -di¯uorobenzophenone with the use of a pseudo- high dilution condition. The structure of the cyclic oligomer was characterized by IR, NMR, matrix-assisted laser desorption ionization time-of-¯ight mass spectroscopy and gel permeation chromatography analyses. From the measurement of wide angle X- ray diraction it was revealed that the cyclic oligomer is crystalline, in contrast to the fact that the corresponding linear polymer is amorphous. The dierence in the crystallization behavior is discussed based on molecular modeling. # 1999 Elsevier Science Ltd. All rights reserved.
1. Introduction The use of macrocyclic oligomers as intermediates for the synthesis of high-performance engineering polymers has been rapidly extended to several systems such as cyclic esters [1, 2], amide [1, 3], ether imides [1], and ether ketones [4±12], since the pioneering work of Brunelle and Shannon on macrocyclic carbonates [13]. In our previous paper on the synthesis and properties of a new cyclic (aryl ether ketone) oligomer (CBAEK) derived from 4,4 0 -di¯uorobenzophenone and bisphenol A, it was revealed that CBAEK possessing an isopropylidene group in the main chain is crystalline in contrast to the fact that the corresponding linear oligomer and polymer are amorphous [14]. The crystallinity of
* Corresponding author. Tel.: 0474-78-0423; fax: 0474-780439; e-mail: [email protected]
the highly methyl-substituted cyclic (aryl ether ketone)s is an interesting problem in relation to the former results. The present paper concerns the synthesis and crystallinity of a tetramethylbiphenol-based cyclic (aryl ether ketone) (CMAEK).
2. Experimental 2.1. Materials All the materials were used as provided. 4,4 0 Di¯uorobenzophenone (m.p. 103±1048C) was received from Yanbian Longjing Chemical Factory. 3,3 0 ,5,5 0 Tetramethyl-4,4 0 -biphenol (TMBPH) was provided by Mitsubishi Chemical Co. Ltd. Toluene, N,N- dimethylformamide (DMF) and potassium carbonate were provided by Aldrich.
0014-3057/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S 0 0 1 4 - 3 0 5 7 ( 9 8 ) 0 0 2 9 2 - 4
1968
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
2.2. Synthesis of CMAEK
To a 1 l three-neck round-bottom ¯ask, which was equipped with a Dean-Stark trap, mechanical stirring, and nitrogen inlet and outlet, were added 500 ml DMF, 30 ml toluene and potassium carbonate (4.15 g, 30.0 mmol). The mixture was heated to re¯ux. The temperature range of the re¯uxing solution was 145± 1488C. A solution of 4,4 0 - di¯uorobenzophenone (5.46 g, 25.0 mmol) and 3,3 0 ,5,5 0 -tetramethyl-4,4 0 biphenol (6.06 g, 25.0 mmol) in 40 ml DMF was added
over an 8 h period via a syringe pump. After the addition was completed, the resulting solution was re¯uxed for another 8 h. The reaction mixture was cooled and ®ltered to remove salts. The ®ltrate was concentrated in vacuo and cooled to room temperature. The obtained precipitate was ®ltered and repeatedly washed with acetone and water (for a total of 10 times), and ®nally dried in vacuo at 1408C for 24 h. The yield of CMAEK was 9.6 g (91% yield).
Fig. 1. IR spectrum of CMAEK.
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
Fig. 2.
19
F-NMR spectra of (a) PMAEK and (b) CMAEK in CDCl3 containing CF3CO2H.
Fig. 3. 1H-NMR spectrum of CMAEK in CDCl3.
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M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
salts. The ®ltrate was concentrated in vacuo and poured into water to precipitate the product. The precipitate was ®ltered and repeatedly washed with acetone and water (for a total of 10 times), and ®nally dried in vacuo at 1408C for 24 h. The yield of PMAEK was 34.7 g (89% yield). 2.4. Measurements IR spectra were measured on a Nicolet 5DX-FTIR spectrometer (KBr method). Wide-angle X-ray diraction (WAXD) was measured on a Shimazu XD-3A Xray diractometer with a scanning rate of 48 min ÿ 1, using CuKa radiation, at 30 kV and 20 mA. Gel permeation chromatography (GPC) analysis was performed on a Shimazu LC-9A instrument equipped with linear two PLgel 5 mm Mixed-D columns (Polymer Laboratories Ltd), using tetrahydrofuran as eluent at pressure 32 kg cm ÿ 2, elution rate 0.5 ml min ÿ 1 and an RI detector. Matrix-assisted laser desorption ionization time-of¯ight mass spectroscopy (MALDI-TOF-MS) analysis was performed on an LDI 1700-TOF-MS (Biomolecular USA). NMR spectra were recorded on a Varian Unity-400 instrument (400 MHz) at 258C, using CDCl3 as solvent. Modeling of the molecular structure based on the MM2 method was performed using Chem3D version 3.1.1 (Cambridge Scienti®c Computing, Inc.). 3. Results and discussion 3.1. Characterization of CMAEK
Fig. 4. 1H-1H DQCOSY NMR spectra of CMAEK in CDCl3.
2.3. Synthesis of the corresponding ¯uorine-terminated linear polymer (PMAEK) To a 1 l three-neck round-bottom ¯ask, which was equipped with a Dean-Stark trap, mechanical stirring, and nitrogen inlet and outlet, were added 4,4 0 -di¯uorobenzophenone (21.8 g, 100 mmol), 3,3 0 ,5,5 0 -tetramethyl- 4,4 0 -biphenol (20.6 g, 85.0 mmol), potassium carbonate (13.8 g, 100 mmol), and 320 ml DMF and 240 ml toluene. The mixture was kept at re¯ux for 6 h. The reaction mixture was cooled and ®ltered to remove
Fig. 1 shows the IR spectrum of CMAEK. No absorption due to a hydroxyl group at around 3400 cm ÿ 1 is observed, indicating that the cyclic oligomer possesses no appreciable terminal hydroxyl group. Fig. 2 shows the 19F-NMR spectra of CMAEK and PMAEK. A signal of terminal ¯uorine atom for PMAEK appeared at ÿ32 ppm relative to the F-signal of tri¯uoroacetic acid used for an internal standard. No appreciable F-signal appeared around ÿ32 ppm in the 19 F-NMR spectrum of CMAEK, indicating the absence of terminal ¯uorine atom. These results suggest that CMAEK has cyclic structure. Figs. 3 and 4 show 1H-NMR and 1H-1H DQCOSY NMR spectra of CMAEK in CDCl3, respectively. The 1 H- signals around 7.7±7.8 ppm and 6.8±6.9 ppm are assigned to Ha and Hb of CMAEK because they are coupled each other. Also, the 1H-signals around 7.2± 7.4 ppm are assigned to Hc because they are coupled with 1H-signals of methyl groups appeared around 2.1±2.2 ppm. Fig. 5(a) and (b) shows 13C-NMR spectra of CMAEK and PMAEK in CDCl3, respectively.
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
Fig. 5. 13C-NMR spectra of (a) PMAEK and (b) CMAEK in CDCl3. (CMAEK: the magni®ed. Therefore, the signal intensity of each carbon cannot be directly compared.
13
1971
C-signals for each carbon are arbitrarily
1972
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
Fig. 6. MALDI-TOF-MS spectrum of CMAEK.
Ten kinds of carbons in the repeating unit of PMAEK are assigned as follows: C1 161.1, C2 114.2, C3 132.3, C4 131.3, C5 194.1, C6 150.0, C7 131.3, C8 127.7, C9 137.8, C10 16.3 ppm. On the other hand, all the signals of C1±10 for CMAEK were split in a complicated pattern. This result indicates that the dierence of ring size of the macrocycle aects the chemical shift of each carbon, and CMAEK consists of many macrocycles with dierent ring size.
macrocycles together with sodium adducts [Mn + Na] + of the desired macrocycles, up to pentameter (n = 5), with reasonable signal to noise ratio (Fig. 6 and Table 1). The GPC chart of CMAEK is shown in Fig. 7, which indicates along with MALDITOF-MS data that the smallest ring (dimer) is the most easily formed.
3.2. Molecular weight distribution of CMAEK
The WAXD spectrum of CMAEK suggests that the cyclic oligomer is crystalline (Fig. 8). On the contrary, no crystalline peak was observed for the corresponding linear polymer (PMAEK). A similar tendency was observed for the previously reported bisphenol A-
3.3. Solid structures of CMAEK
The MALDI-TOF-MS spectrum of CMAEK, using 2,5-dihydroxybenzoic acid as the matrix material, gives the correct molecular ion peaks [Mn] + for the desired Table 1 MALDI-TOF-MS data of CMAEK Signal (m/e)
Relative intensity (%)
Assignmenta
Calculated m/e
Deviationb
841.3 1261.2 1684.0 2104.0
100 50 30 20
M2 M3 M4 M5
841.0 1261.5 1682.0 2102.5
+ 0.3 ÿ0.3 + 2.0 + 1.5
a Mx represents the molecular ion with x repeating units; the average molecular weights calculated for repeating unit C29H24O3 = 420.5. b Deviation = (experimental value)-(calculated value).
M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
1973
Fig. 7. GPC trace of CMAEK.
based cyclic (aryl ether ketone) (CBAEK) and the corresponding linear oligomers. Considering that these cyclic and linear compounds have the highly methylsubstituted structure, it is interesting that only the cyclic oligomer is crystalline. Modeling based on MM2 method for both cyclic and linear dimers was performed in order to clarify a factor of the crystallization of the highly methyl-substituted macrocycle. As shown in Fig. 9, tetramethylbiphenol-based cyclic (aryl ether ketone) dimer (CMAEK (n = 2)) and its unsubstituted derivative had a similar conformation regardless of the methyl substitution. In contrast to this result, the conformation of tetramethylbiphenol-based linear (aryl ether ketone) dimer (PMAEK (n = 2)) was highly deviated from that of its unsubstituted linear dimer
Fig. 8. WAXD pattern of CMAEK.
(Fig. 10). The terminal benzophenone moiety and tetramethylbiphenylene moiety of PMAEK (n = 2)) are very far apart because of the steric hindrance, as compared with its unsubstituted derivative. Although we cannot discuss the strict conformational change because the molecular structure is not an energy-optimized structure, it is apparent that the conformational change of the linear oligomer by the methyl substitution is much larger than that of the cyclic one. The
Fig. 9. Molecular structure of (a) CMAEK (n = 2) and (b) its unsubstituted derivative calculated by MM2 method.
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M. Shibata et al. / European Polymer Journal 35 (1999) 1967±1974
Fig. 10. Molecular structure of (a) PMAEK (n = 2) and (b) its unsubstituted derivative calculated by MM2 method.
rigid and symmetrical conformation for the cyclic oligomers regardless of the methyl substitution is thought to be related to their crystallization. X-ray single crystal analyses of these oligomers are now under investigation in order to clarify this reasoning.
4. Conclusions A cyclic (aryl ether ketone) oligomer containing tetramethylbiphenylene moiety was synthesized by the reaction of 3,3 0 ,5,5 0 -tetramethylbiphenol and 4,4 0 di¯uorobenzophenone with the use of pseudo-high dilution condition. From the measurement of wide angle X-ray diraction it was revealed that the cyclic oligomer is crystalline in contrast to the fact that the corresponding linear polymer is amorphous. From the consideration by the modeling based on MM2 method, it was expected that the crystallization of the cyclic oligomer is attributed to its rigid and symmetrical conformation as compared with the corresponding linear oligomer.
References [1] Guggenheim TL, McCormick SJ, Kelly JJ, Brunelle DJ, Colley AM, Boden EP, Shannon TG. Polym Prepr (Am Chem Soc, Div Polym Chem) 1989;30(2):579. [2] Hodge P, Houghton MP, Lee MSK. J Chem Soc, Chem Commun 1993;6:581. [3] Memeger W, Jr, Lazar J, Ovenall D, Leach RA. Macromolecules 1993;26:3476. [4] Wang Y-F, Chan Kwok P, Hay AS. J Polym Sci, Part A: Polym Chem 1996;34:374. [5] Chan Kwok P, Wang Y-F, Hay AS. Macromolecules 1995;28:6705. [6] Chan Kwok P, Wang Y-F, Hay AS. Macromolecules 1995;28:653. [7] Gao C, Hay AS. Polymer 1995;36:4141. [8] Chen M-F, Gibson HW. Macromolecules 1996;29:5502. [9] Chen M-F, Fronczek F, Gibson HW. Macromol Chem Phys 1996;197:4069. [10] Teasley MF, Hsiao BS. Macromolecules 1996;29:6432. [11] Ding Y, Hay AS. Macromolecules 1996;20:3090. [12] Jiang H, Chen T, Qi Y, Xu J. Polymer J. 1998;30:300. [13] Brunelle DJ, Shannon TG. Macromolecules 1991;24:3035. [14] Shibata M, Yosomiya R, Chen C, Wang J, Wu Z. Angew Makromol Chem, in press.