Article pubs.acs.org/Macromolecules
Precise Synthesis and Characterization of Tadpole-Shaped Polystyrenes with High Purity Yuya Doi,† Yutaka Ohta,† Masahide Nakamura,‡ Atsushi Takano,*,† Yoshiaki Takahashi,§ and Yushu Matsushita† †
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan ‡ Scientific Instruments Division, Shoko Scientific Co., Ltd., 1-3-3, Azaminominami, Aoba-ku, Yokohama, Kanagawa. 225-0012, Japan § Institute for Materials Chemistry and Engineering, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan ABSTRACT: Tadpole-shaped polystyrenes (PS) were successfully synthesized anionically by coupling reaction between ring polystyrene with two functional groups and living linear polystyrenes. Crude coupling product was confirmed to include unreacted linear tail polymer and tadpole polymer having one tail (single-tail tadpole polymer) and two tails (twin-tail tadpole polymer) by SEC analysis. In order to isolate the tadpole polymers, interaction chromatography (IC) was conducted to remove the linear polymer from the crude product; subsequently, two kinds of tadpole polymers were carefully separated by SEC fractionation. It has been found by SEC-MALS that the absolute molecular weights of the two fractionated products agree well with the sums of the component ring and linear chains, which prove two tadpole polymers, i.e., single-tail and twin-tail, were obtained as designed. It was confirmed that the two tadpole polymers have high molecular weight (58k for ring and 67k for a tail), narrow molecular weight distribution (Mw/Mn = 1.01), and high purity over 99% by rigorous HPLC analyses.
1. INTRODUCTION Over the past several decades, a number of studies on ring polymers have been extensively pursued theoretically1−9 and experimentally10−23 because they are of great interest in investigation of topological effects on their physical properties such as solution, viscoelastic properties and so on. However, due to a lack of rigorous separation method for ring polymers from linear contaminants of similar molecular size, the purity of the rings was not clarified for most of the experimental studies. Therefore, it was unclear whether samples purified by standard separation methods, i.e., fractional precipitation or preparative size exclusion chromatography (SEC), were fully pure or not. Recently novel HPLC techniques called liquid chromatography at critical condition (LCCC) and interaction chromatography (IC) were developed, and these methods enable to separate rings from linear chains.24,25 The LCCC technique was applied to the characterization of nine ring polystyrenes synthesized by Roovers et al., and it was quantitatively confirmed that they were contaminated with as much as 10−25% linear polymers. Furthermore, the LCCC was utilized for the purification of the ring samples, and the pure ring samples obtained were employed in viscoelastic measurements.21 As a result, it has been found that the pure rings do not reveal apparent rubbery plateau, and they relax faster than linear chains. Moreover, surprisingly it was also found out that a drastic recovery of rubbery plateau was observed when only a small amount of linear polymer with the same molar mass as ring polymer was © 2013 American Chemical Society
added, furthermore a relaxation time of the blended sample becomes longer than that for the simple linear polymer. These results clearly indicate that ring polymers show completely different viscoelastic properties from linear ones due to the topological effects, and the linear contamination affects the viscoelasticity of ring chains remarkably. Taking these interesting experimental facts mentioned above into account, it is considered that a polymer possessing both ring and linear chain in one molecule, which can be called “tadpole-shaped polymer”, might be a quite intriguing model polymer from viscoelastic aspects. For example, if a linear chain of a tadpole polymer entangles with a ring chain of the other molecule, strong intermolecular entanglement network could be formed, while if intramolecular entanglements are formed within a molecule preferentially, they are able to behave like pure rings. Not only the viscoelastic properties but also the other physical properties such as solution properties of the tadpole polymers are interesting to investigate. For example, theta temperature depression of the ring polymer in a theta solvent was theoretically predicted by taking a topological repulsive interaction of chain segments into consideration,26−29 whereas the theta temperature lowering was experimentally observed in Received: December 6, 2012 Revised: December 27, 2012 Published: January 18, 2013 1075
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Scheme 1. Synthesis of Telechelic Polystyrene with DPE-Type Double Bonds on Both Ends
Scheme 2. Cyclization of Telechelic Polystyrene and Introduction of DPE-Type Double Bonds
ring polystyrenes/cyclohexane systems.30,31 Along this line the theta temperature of a tadpole polymer is a fascinating topic to explore from the viewpoint of solution properties. In practice, several reports for syntheses of tadpole polymers have been made using various kinds of synthetic approach so far.32−49 However, tadpole polymers with relatively low molecular weight were merely prepared, moreover they were not suitable for viscoelastic measurements, since rigorous purification of the samples was not achieved. In this study, therefore, we prepared tadpole-shaped polystyrenes by a coupling reaction among a highly purified ring polystyrene having two functional groups with living linear polystyrenes. The sample was purified by multistep HPLC fractionation procedures. The prepared tadpole-shaped samples with high purity were carefully characterized by SEC-MALS measurements. Furthermore, elution behavior of the tadpole-shaped polymers was investigated by HPLC analyses using SEC, LCCC, and IC modes.
ring-closure reaction of telechelic polystyrene, it being synthesized by an anionic polymerization followed by two-step end-capping reactions, using DPE and CPPE, as shown in Scheme 1. The details of experimental procedures were reported previously.50 The telechelic polystyrene was transferred into a glass apparatus and dissolved in purified THF under reduced pressure at polymer concentration of ca. 0.1% w/v. Excess amount of potassium naphthalenide as a linking agent was added to the diluted polymer solution at room temperature and stirred for 1 day. Then after the capping reaction with DPE, CPPE was added so as to introduce DPE type double bonds as reactive groups for later use as shown in Scheme 2. The product obtained was precipitated into an excess amount of methanol three times. 2.2.2. Purification of Ring Polystyrene. Since the cyclization product mentioned in the previous section was found to contain various kinds of polycondensation products in addition to unreacted telechelic polymer, three fractionation procedures were conducted to obtain ring polystyrene with high purity. First a precipitational fractionation was carried out to remove high molecular weight polycondensation products in cyclohexane. Second, LCCC fractionation was conducted to exclude unreacted linear polystyrene. The equipment was a preparative HPLC system consisting of a HPLC pump, DP-8020 (Tosoh Co.), a UV detector, UV-8020 (wavelength 254 nm, Tosoh Co.), an autosample injector, SSC-1300 (Senshu Scientific Co.) with a 500 μL sample loop, and a fraction collector, FC203B (Gilson Inc.). Two preparative bare-silica columns (5SIL10E, 250 mm length, 10.0 mm i.d., Shodex Co.) were used. The mobile phase was a mixture of n-hexane and THF (58/42 in volume), and the flow rate was 3.0 mL/min. The sample was dissolved in the mobile phase at a concentration of 1.5% w/v. The column temperature was adjusted at 33.5 °C by circulating a fluid through a column jacket with a programmable bath/circulator, P2-C25P (HAAKE). After the LCCC fractionation, SEC fractionation was carried out using the same preparative HPLC system equipped with two SEC silica gel columns (PROTEIN KW-804, 300 mm length, 8.0 mm i.d., Shodex Co.). Although these columns are normally water-specified ones, a water-soluble organic solvent, THF, was used as a mobile phase in the present study. The sample was dissolved in the mobile phase, THF, at a concentration of 1.0% w/v. Column temperature was kept at 40 °C by column oven CO-8020 (Tosoh Co.), and the flow rate was 1.0 mL/min. 2.2.3. Preparation of Tadpole-Shaped Polystyrene. The ring polystyrene with high purity obtained by three fractionation methods was reacted with living linear polystyrene chains (Scheme 3). First, styrene was anionically polymerized with sec-butyllithium in THF at
2. EXPERIMENTAL SECTION 2.1. Materials. Potassium naphthalenide was synthesized by the same procedure as reported previously.50 sec-Butyllithium was purchased from Asia Lithium Co. Ltd. and diluted with purified nhexane. Tetrahydrofuran (THF, Hayashi Pure Chemicals Co. Ltd.) was dried over sodium metal and distilled in vacuo with sodium anthracenide, followed by distillation from a mixture of αmethylstyrene tetramer sodium dianion. Styrene (Kishida Reagents Chemicals Co. Ltd.) was dried over calcium hydride under reduced pressure and successively purified by distillation with octylbenzophenone sodium. 1,1-Diphenylethylene (DPE, Hokko Chemicals Co. Ltd., 95%) were dried over calcium hydride under reduced pressure, followed by purification with n-butyllithium. 1-[3-(3Chloropropyldimethylsilyl)phenyl]-1-phenylethylene (abbreviated as CPPE) was synthesized and purified in the same manners as reported previously.51 For HPLC analysis and HPLC fractionation, THF (industrial grade, Daishin Chemical Co.) and n-hexane (reagent grade, Kishida Chemical Co.) were used as received. For precipitational fractionation, cyclohexane (reagent grade, Kishida Chemical Co.) was also used as received. 2.2. Preparation of Tadpole-Shaped Polystyrene. 2.2.1. Synthesis of Ring Polystyrene Having Functional Groups with High Purity. Synthesis of ring polystyrene was carried out by an end-to-end 1076
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Scheme 3. Synthesis of Tadpole-Shaped Polystyrenes
−78 °C to give a living linear polymer, the solution being gradually added to the THF solution of the ring polystyrene. The molar ratio of [living linear polystyrene]/[ring polystyrene] was approximately 4; the coupling reaction kept going for 36 h. The polymer obtained was precipitated into an excess amount of methanol. The crude coupling product was found to contain single-tail tadpole polystyrene (called “single-tail PS”), twin-tail tadpole polystyrene (called “twin-tail PS”), and unreacted linear polystyrene. First IC fractionation of the coupling product was conducted to remove the unreacted linear polymers from the coupling product. The equipment, the columns, and the mobile phase for the IC fractionation were the same as for the LCCC described above except for the column temperature (at 27 °C). Second, SEC fractionations for rigorous separation of two kinds of tadpole-shaped polystyrenes were conducted in the same condition for the SEC purification of ring polystyrene described above. 2.3. Molecular Characterization. Weight-average molecular weights, Mw, of the samples were measured by light scattering in THF at 35 °C with a multiangle light scattering apparatus, MALS, Dawn-EOS (Wyatt Technology Co.), while their molecular weight distribution, Mw/Mn, was determined by SEC in the same condition for the SEC fractionations described above. All samples were dissolved in the mobile phase, THF, at a concentration of 0.1−0.2% w/v. The SEC-MALS measurements were also carried out to measure Mw and radii of gyration, Rg, of polymers simultaneously. The SEC system was composed of SEC pump, PU-908 (JASCO Co.), a column oven, CO-2065 plus (JASCO Co.), and three SEC columns, KW-804. The eluent was THF, and the flow rate was 1.0 mL/min. All samples were dissolved in the eluent, THF, at a polymer concentration of 0.2% w/v. The column temperature was kept constant at 40 °C. A MALS detector, DAWN HELEOS II (Wyatt Technology Co.), and a differential refractive index detector, Optilab rEX (Wyatt Technology Co.), were connected to the SEC system. The HPLC analysis was carried out by the same apparatus as the LCCC fractionation. All samples were dissolved in a mixture of THF/ n-hexane (42/58 in volume) at a polymer concentration of 0.1% w/v. The column temperature was adjusted in the range from 20 to 50 °C.
Figure 1. SEC chromatograms of (a) a telechelic polystyrene, (b) the cyclization reaction product, and (c) the product after precipitational fractionation in cyclohexane.
(HPLC) fractionation was carried out. Figure 2a compares HPLC chromatograms of three PS standards (Mw = 10.2k, 37.9k, and 96.4k, Tosoh Co.) at different temperatures ranging from 20 to 50 °C to search the chromatographic critical condition. Figure 2b shows a plot of logarithmic Mw versus elution time for standard PS samples at various temperatures. From this plot a chromatographic critical temperature for linear polystyrenes was clearly determined to be 33.5 °C, at which the size exclusion contribution and interaction one are just canceled out. Furthermore, it was also confirmed from Figure 2b that the elution behavior corresponds to SEC mode above 33.5 °C, while IC mode below the critical temperature. Using the critical condition for linear polystyrenes thus obtained, LCCC measurement for the cyclization product after precipitational fractionation was carried out as displayed in Figure 3a, and the corresponding SEC chromatogram is shown in Figure 3d. In Figure 3a, linear and ring polymers were eluted at around 11 and 14 min, respectively, while SEC peaks in Figure 3d are overlapped partly. These facts clearly tell that a linear and a ring polymer can be separated with high resolution by this LCCC method, and hence LCCC fractionation was conducted. The fractionation area was designated as #1 in Figure 3a where double vertical bars indicate the fraction boundaries. The fractionated product was analyzed by LCCC and SEC as shown in Figures 3b and 3e, respectively. From Figure 3b, it is evident that the linear polymer was removed by this fractionation, while 4% of dimeric ring remained as shown in Figure 3e. Then further SEC fractionation in the range designated as #2 in Figure 3e was conducted. Figures 3c and 3f compare the LCCC and SEC chromatograms of the SECfractionated product. The SEC chromatogram of the final product in Figure 3f possesses single and symmetrical peak, which indicates that the monomeric ring polymer was completely separated by the SEC fractionation. The purity of the ring polymer was estimated to be 99.9% from the LCCC chromatogram in Figure 3c. Thus, the ring polystyrene with functional groups with ultrahigh purity was obtained (1.6 g, Mw = 57 600, Mw/Mn = 1.02). 3.2. Preparation of Tadpole-Shaped Polystyrene. Using the ring polystyrene obtained above, tadpole-shaped polystyrenes were prepared by synthetic Scheme 3. Approx-
3. RESULTS AND DISCUSSION 3.1. Preparation of Ring Polystyrene with High Purity. In this study telechelic polystyrene (Mw = 60 700, Mw/Mn = 1.04) of total 7.6 g was cyclized. Figures 1a and 1b compare the SEC chromatograms of the telechelic polystyrene and the crude cyclization reaction product. From the peak area analysis of the SEC chromatogram, the cyclization product includes ca. 40% of ring polystyrene eluted at 19.2 min, accompanied by several kinds of polycondensation products and also unreacted linear precursor. Figure 1c shows the SEC chromatogram of a product after precipitational fractionation in cyclohexane. It is evident that most of the high molecular weight polycondensation products were removed by the precipitational fractionation, and 3.3 g of the fractionated product with ring polymer content of ca. 70% was recovered. To exclude the unreacted linear precursor from the fractionated product, high performance liquid chromatography 1077
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Figure 4. SEC chromatograms of (a) highly purified ring polystyrene, (b) living linear polystyrene, (c) the product of the coupling reaction of ring polystyrene in (a) and linear polystyrene in (b), (d) the fraction after IC fractionation of the coupling reaction product, and (e) the fraction #3 (= product I) and (f) the fraction #4 (= product II).
imately 4 M amount of linear living polystyrene (1.5 g, Mw = 67 200, Mw/Mn = 1.02; Figure 4b) was reacted with the ring polystyrene (0.32 g; Figure 4a). After the coupling reaction, the product showed multipeak chromatogram as shown in Figure 4c. In this chromatogram, the peak for the ring polymer (19.2 min) mostly disappeared, and two new peaks appeared at 15.0 min (ca. 46%) and 16.2 min (ca. 11%), which is called product
Figure 2. (a) HPLC chromatograms of standard polystyrenes (Mw = 10.2k, 37.9k, and 96.4k) at different temperatures ranging from 20 to 50 °C. (b) A plot of logarithmic Mw versus elution time for standard PS samples at various temperatures.
Figure 3. LCCC chromatograms of (a) the cyclization product after precipitational fractionation, (b) the fraction #1 after LCCC fractionation, and (c) the fraction #2 after LCCC and SEC fractionations. SEC chromatograms of (d), (e), and (f) are corresponding to the sample (a), (b), and (c), respectively. 1078
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Mw of product II (124k) agrees with the sum (125k) of Mw of R-PS and L-PS. These results clearly indicate that products I and II are definitely single-tail PS and twin-tail PS as designed. By using the Rg data for four samples, g-factor was estimated, which reveals the shrinking index defined by
I and product II, respectively. In order to remove the unreacted linear polymer from the reaction product, IC fractionation was conducted, and then most of the linear polymers were successfully removed and the fractionated product showed a chromatogram with double peak as shown in Figure 4d. In order to isolate the product I and II from the reaction product, the SEC fractionation was conducted, in the range designated as #3 and #4 in Figure 4d. The SEC chromatogram of the fractionated product for the fraction #3 (product I, 0.34 g) as shown in Figure 4e has single and symmetrical peak with the purity of 99.6%, while that for the fraction #4 (Product II, 0.039 g; Figure 4f) gives also the single and symmetrical peak with the purity of 99.6%. 3.3. SEC-MALS Measurement. In order to measure the weight-average molecular weights (Mw) and radii of gyration (Rg) for the products I and II, ring polystyrene (R-PS) and the linear polystyrene as the tadpole tail (L-PS), SEC-MALS measurements were carried out. Figure 5 exhibits the SEC
g = ⟨R g 2⟩(tadpole or ring) /⟨R g 2⟩(linear)
which is the ratio of mean-square radii of gyration of tadpole molecules or ring molecule to linear one with the same molecular weight. The radius of gyration of the linear polystyrene was calculated from the following Rg−Mw relationship in THF R g = 0.0098M w 0.61 (nm, linear PS, in THF)
chromatograms of the four samples combined with the corresponding Mws and Rg in THF as vertical axes, and Table 1 summarizes the molecular characteristics of four samples. It appears that Mw of product I (197k) agrees well with the sum (192k) of Mw of R-PS and double Mw of L-PS. In the same way,
4. CONCLUSION Tadpole-shaped polystyrenes with single-tail and twin-tail were successfully synthesized by coupling reaction between ring polystyrene with two functional groups and living polystyrenes. Crude coupling product was confirmed to include unreacted linear tail polymer, single-tail tadpole polymer, and twin-tail tadpole polymer by SEC analysis. In order to isolate the tadpole polymers, IC and SEC fractionation procedures were conducted. As a result, it was confirmed by SEC-MALS that the absolute molecular weights of the two fractionated products agree well with the sum of the component ring and linear polymers, which proves the tadpole polymers with single-tail or twin-tail were successfully obtained. Furthermore, it was clarified that the two tadpole polymers with high molecular
Table 1. Molecular Characteristics of Four Polymers Measured by SEC-MALS and HPLC
Mw/Mnb purity (%)b Rg (nm)a g1/2 a
twin-tail
single-tail
L-PS
R-PS
197 000 1.01 99.6 13.3 0.80
124 000 1.01 99.6 10.8 0.86
67 200 1.02
57 600 1.02 99.9 5.3 0.67
8.4 0.97
(2)
which is given by the SEC-MALS measurement using standard polystyrene samples (Mw = 9.1k, 37.9k, 96.4k, and 427k, Tosoh Co.). In this study g1/2 for the ring polymer (R-PS) was obtained as 0.67, which is slightly smaller than the theoretical value of 1/√2 (= 0.707) for a Gaussian ring.2 g1/2 for the twintail PS and the single-tail PS are 0.80 and 0.86, respectively, both of which are evidently larger than that for a simple ring. These results indicate that tadpole PSs possess the intermediate conformation of a linear and a ring polymer in dilute solution. This is natural because a single-tail polymer includes a linear and a ring in one molecule. Moreover, the twin-tail PS has a smaller g-factor value than the single-tail PS. The connecting point of the latter has three branches, while that of the former dose four. This means the segment density of the twin-tail PS is higher than that of the single-tail PS, therefore it is quite reasonable that the twin-tail PS has a smaller g-factor value than the single-tail PS. 3.4. HPLC Measurements. Figure 6a shows a series of HPLC chromatograms of three PS standards (Mw = 10.2k, 37.9k, and 96.4k, Tosoh Co.) at different temperatures ranging from 20 to 50 °C to search the chromatographic critical condition, where the LCCC condition for linear polystyrenes was determined to be 33.5 °C. Accordingly, SEC condition appears in the temperature range above the critical point, while IC condition appears below the critical point. Figure 6b compares the chromatograms for four samples of twin-tail PS (red), single-tail PS (blue), L-PS (orange), and R-PS (green) in the temperature range of 20 to 50 °C. This figure clearly indicates that the elution behavior of two kinds of tadpole PSs is sensitively varied by changing the temperature. In particular, two kinds of tadpole PSs, single-tail PS and twin-tail PS, can be separated clearly at 20 °C, which is giving with strong IC condition.
Figure 5. SEC chromatograms of four samplestwin-tail PS, singletail PS, L-PS, and R-PScombined with the corresponding (a) absolute Mws and (b) radii of gyration (Rg) in THF.
Mwa
(1)
Measured by SEC-MALS. bMeasured by HPLC. 1079
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Figure 6. HPLC chromatograms of (a) standard polystyrenes and (b) four present samples, i.e., twin-tail PS, single-tail PS, L-PS, and R-PS, at different temperatures ranging from 20 to 50 °C. (12) Roovers, J.; Toporowski, P. M. Macromolecules 1983, 16, 843− 849. (13) Roovers, J. Macromolecules 1985, 18, 1359−1361. (14) Hadziioannou, G.; Cotts, P. M.; ten Brinke, G.; Han, C. C.; Lutz, P.; Strazielle, C.; Remmp, P.; Kovacs, A. J. Macromolecules 1987, 20, 493−497. (15) McKenna, G. B.; Hadziioannou, G.; Lutz, P.; Hild, G.; Strazielle, C.; Straupe, C.; Remmp, P.; Kovacs, A. J. Macromolecules 1987, 20, 498−512. (16) Mills, P. J.; Mayer, J. W.; Kramer, E. J.; Hadziioannou, G.; Lutz, P.; Strazielle, C.; Remmp, P.; Kovacs, A. J. Macromolecules 1987, 20, 513−518. (17) Roovers, J.; Toporowski, P. M. J. Polym. Sci., Part B 1988, 26, 1251−1259. (18) Roovers, J. Macromolecules 1988, 21, 1517−1521. (19) McKenna, G. B.; Hostetter, B. G.; Hadjichristidis, N.; Fetters, L. J.; Plazek, D. J. Macromolecules 1989, 22, 1834−1521. (20) Kawaguchi, D.; Masuoka, K.; Takano, A.; Tanaka, K.; Nagamura, T.; Torikai, N.; Dalgliesh, R. M.; Langridge, S.; Matsushita, Y. Macromolecules 2006, 39, 5180−5182. (21) Kapnistos, M.; Lang, M.; Vlassopoulos, D.; Pyckhout-Hintzen, W.; Richter, D.; Cho, D.; Chang, T.; Rubinstein, M. Nat. Mater. 2008, 7, 997−1002. (22) Bras, A. R.; Pasquino, R.; Koukoulas, T.; Tsolou, G.; Holderer, O.; Radulescu, A.; Allgaier, J.; Mavrantzas, V. G.; Pyckhout-Hintzen, W.; Wischnewski, A.; Vlassopoulos, D.; Richter, D. Soft Matter 2011, 7, 11169−11176. (23) Takano, A.; Ohta, Y.; Masuoka, K.; Matsubara, K.; Nakano, T.; Hieno, A.; Itakura, M.; Takahashi, K.; Kinugasa, S.; Kawaguchi, D.; Takahashi, Y.; Matsushita, Y. Macromolecules 2012, 45, 369−373. (24) Pasch, H.; Trathnigg, B. HPLC of Polymers; Springer: Berlin, 1998. (25) Lee, H. C.; Lee, H.; Lee, W.; Chang, T.; Roovers, J. Macromolecules 2000, 33, 8119−8121. (26) Iwata, K.; Kimura, T. J. Chem. Phys. 1981, 74, 2039−2048. (27) Iwata, K. Macromolecules 1985, 29, 115−116. (28) Tanaka, F. J. Chem. Phys. 1987, 87, 4201−4206. (29) Deguchi, T.; Tsurusaki, K. Proc. Lect. Knots 96 1997, 95. (30) Roovers, J. J. Polym. Sci., Part B 1985, 23, 1117−1126. (31) Takano, A.; Kushida, Y.; Ohta, Y.; Masuoka, K.; Matsushita, Y. Polymer 2009, 50, 1300−1303. (32) Beinat, S.; Schapparcher, M.; Deffieux, A. Macromolecules 1996, 29, 6737−6743.
weight and narrow molecular weight distribution reveal ultrahigh purity over 99% by rigorous HPLC analyses. Using the tadpole polystyrenes with high purity, their viscoelastic and solution properties will be reported in the near future.
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AUTHOR INFORMATION
Corresponding Author
*Phone +81-52-789-3211; Fax +81-52-789-3210; e-mail
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS The authors gratefully thank Professor Masami Kamigaito and Dr. Kanji Nagai of Nagoya University for their helps in SECMALS measurement. This work was supported in part by a Grant-in-Aid for Scientific Research (No. 24350056) from the Ministry of Education, Science and Culture (MEXT), Japan. We also acknowledge for the financial support from the Global 30 international program at Nagoya University and the Program for Leading Graduate Schools at Nagoya University entitled“Integrate Graduate Education and Research Program in Green Natural Sciences.
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REFERENCES
(1) Kramers, H. A. J. Chem. Phys. 1946, 14, 415−424. (2) Zimm, B. H.; Stockmayer, W. H. J. Chem. Phys. 1949, 17, 1301− 1314. (3) Casassa, E. F. J. Polym. Sci., Part A 1965, 3, 605−614. (4) Prentis, J. J. J. Chem. Phys. 1982, 76, 1574−1583. (5) Douglas, J. F.; Freed, K. F. Macromolecules 1984, 17, 2344−2354. (6) Cates, M. E.; Deutsch, J. M. J. Phys. (Paris) 1986, 47, 2121−2128. (7) Klein, J. Macromolecules 1986, 19, 105−118. (8) Rubinstein, M. Phys. Rev. Lett. 1986, 24, 3023−3026. (9) Obukhov, S. P.; Rubinstein, M.; Duke, T. Phys. Rev. Lett. 1994, 73, 1263−1266. (10) Higgins, J. S.; Dodgson, K.; Semlyen, A. Polymer 1979, 20, 553− 558. (11) Vollmert, B.; Huang, J. X. Makromol. Chem., Rapid Commun. 1981, 2, 467−472. 1080
dx.doi.org/10.1021/ma302511j | Macromolecules 2013, 46, 1075−1081
Macromolecules
Article
(33) Kubo, M.; Hayashi, T.; Kobayashi, H.; Itoh, T. Macromolecules 1998, 31, 1053−1057. (34) Oike, H.; Washizuka, M.; Tezuka, Y. Macromol. Rapid Commun. 2001, 22, 1128−1134. (35) Oike, H.; Uchibori, A.; Tsuchitani, A.; Kim, H. K.; Tezuka, Y. Macromolecules 2004, 37, 7595−7601. (36) Adachi, K.; Irie, H.; Sato, T.; Uchibori, A.; Shiozawa, M.; Tezuka, Y. Macromolecules 2005, 38, 10210−10219. (37) Li, H.; Debuigne, A.; Jerome, R.; Lecomte, P. Angew. Chem., Int. Ed. 2006, 45, 2264−2267. (38) Li, H.; Jerome, R.; Lecomte, P. Polymer 2006, 47, 8406−8413. (39) Li, H.; Riva, R.; Jerome, R.; Lecomte, P. Macromolecules 2007, 40, 824−831. (40) Shi, G.; Tang, X.; Pan, C. J. Polym. Sci., Part A 2008, 46, 2390− 2401. (41) Dong, Y.; Tong, Y.; Dong, B.; Du, F.; Li, Z. Macromolecules 2009, 42, 2940−2948. (42) Li, L.; He, W.; Li, J.; Han, S.; Sun, X.; Zhang, B. J. Polym. Sci., Part A 2009, 47, 7066−7077. (43) Wan, X.; Liu, T.; Liu, S. Biomacromolecules 2011, 12, 1146− 1154. (44) Lonsdale, D. E.; Monteiro, M. J. J. Polym. Sci., Part A 2011, 49, 4603−4612. (45) Dedeoglu, T.; Durmaz, H.; Hizal, G.; Tunca, U. J. Polym. Sci., Part A 2012, 50, 1917−1925. (46) Jia, Z.; Monteiro, M. J. J. Polym. Sci., Part A 2012, 50, 2085− 2097. (47) Wang, G.; Hu, B.; Fan, X.; Zhang, Y.; Huang, J. J. Polym. Sci., Part A 2012, 50, 2227−2235. (48) Huang, B.; Fan, X.; Wang, G.; Zhang, Y.; Huang, J. J. Polym. Sci., Part A 2012, 50, 2444−2451. (49) Fan, X.; Huang, B.; Wang, G.; Huang, J. Polymer 2012, 53, 2890−2896. (50) Takano, A.; Kondo, K.; Ueno, M.; Ito, K.; Kawahara, S.; Isono, Y.; Suzuki, J.; Matsushita, Y. Polym. J. 2001, 33, 732−740. (51) Cho, D.; Masuoka, K.; Koguchi, K.; Asari, T.; Kawaguchi, D.; Takano, A.; Matsushita, Y. Polym. J. 2005, 37, 506−511.
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