Functional Polymers

Modulation of reversible self-assembling of dumbbell-shaped poly(ethylene glycol)s and β-cyclodextrins: precipitation and heat-induced supramolecular crosslinking

Abstract

A series of dumbbell-shaped poly(ethylene glycol) (PEG) chains 1 attached to bulky end groups were prepared, and some of the chains formed supramolecular assemblies with β-cyclodextrin (β-CD) and its multiple, ditopic and tetratopic, derivatives. The chains with proper end groups successfully allowed β-CD to be trapped onto PEG through formation of hydrogen bonds at room temperature and higher. Mixing of the PEG chain and the ditopic supramolecular crosslinker in water at 40 °C led to a change in solution property from viscous to elastic, accompanied by a significant increase in viscosity, whereas this change was not induced at room temperature. A supramolecular network formed only when the PEG chain was mixed with the tetratopic supramolecular crosslinker at 40 °C. Once formed, the supramolecular crosslinking was maintained even after the system cooled down. Instead, dilution and shaking at room temperature resulted in a return to a solution with low viscosity. These assemblies and dissociations were affected by the end groups of 1.

Introduction

One of the greatest findings in the 1990s was the self-assembly of cyclic molecules onto a linear polymeric chain, represented by α-cyclodextrin (α-CD) onto poly(ethylene glycol) (PEG)1, 2 and β-cyclodextrin (β-CD) onto poly(propylene glycol),3, 4 leading to the development of supramolecular materials based on cyclodextrins5, 6, 7, 8 and others.9, 10 In the assembly, CD molecules formed intermolecular hydrogen bonds2, 4, 6, 7 with each other to stay on the chain while threading and dethreading were competing, and finally a supramolecular assembly called pseudopolyrotaxane was obtained as a kinetic product. As a matter of course, some thermodynamic advantages accompanied this process, such as enthalpic gain on forming hydrogen bonds,6 and total entropic changes on assembly of the components, as well as desolvation. It seems that PEG and poly(propylene glycol) chains provided a suitable guide for α-CD and β-CD to fill the size-matched cavity and align cooperatively through formation of hydrogen bonds. In recent years, Takata et al. reported an excellent synthetic approach for yielding pseudopolyrotaxanes based on self-assembly of modified CD molecules onto a linear polymeric chain without relying on forming hydrogen bonds, but using heterogeneous systems in which permethylated α-CD and poly(tetrahydrofuran) or PEG were used in hydrocarbon solvents11 as well as in water.12 Even though the initial 1:1 complex is not necessarily preferred to form, threading occurs sequentially and the complexation reaction proceeds because dethreading is retarded through kinetic and/or thermodynamic stabilization of intermediary complexes in a cooperative manner, which seems unfavorable for a size-mismatched combination (Scheme 1a).2 Each cyclic molecule enters on threading and leaves at the end of a chain. Setting up a barrier at each end of a chain affects both entering and leaving,6, 7 and brings about changes in the ratio of kn/k−n. A precise barrier ideally allows a cyclic molecule to remain on any chain, instead of relying on specific combinations of cyclic and linear components with size adequacy (Scheme 1b). In addition, cyclic molecules would stay on chains cooperatively when they were crosslinked by a spacer, leading to a supramolecular network through the pseudopolyrotaxane formation (Scheme 1c).13, 14, 15, 16, 17

Here we report the roles of barriers at the ends of a chain, and crosslinking of cyclic molecules in self-assembly of size-mismatched components, PEG and β-CD.17, 18, 19 We investigated systematically the pseudopolyrotaxane formation of a series of dumbbell-shaped PEG chains 1ae with native β-CD 2 and its permethylated derivative 320 (Scheme 1b and Figure 1). Two crosslinked β-CD derivatives, ditopic 417 and tetratopic 5, were used to form a supramolecular network on mixing with 1 in water (Scheme 1c and Figure 1).

Figure 1
figure1

Chemical structures of dumbbell-shaped poly(ethylene glycol) chains 1ae, β-cyclodextrin 2, permethylated β-cyclodextrin 3, ditopic crosslinker 4 and tetratopic crosslinker 5.

Experimental procedure

Materials

Poly(ethylene glycol)s (average Mn: 380–420 and 950–1050) were purchased from Aldrich Co. Ltd. (St Louis, MO, USA), and used as a starting material to prepare PEG bis(prop-2-ynyl) ether 7 (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry m/z 513 ([M(m=9)+Na]+, BP),21 and PEG bis(2-aminoethyl) ether (matrix-assisted laser desorption/ionization time-of-flight MS m/z 1096 ([M(n=22)+Na]+, BP).22 Pentaerythritol ethoxylate 16 (average Mn: 797) was purchased from Aldrich Co. Ltd., and derived to quadruply-azidated 10. Heptakis(2,3-di-O-methyl)-hexakis(6-O-methyl)-6-monodeoxy-6-monoazido-β-CD 8 and heptakis(2,3-di-O-methyl)-hexakis(6-O-methyl)-6-monodeoxy-6-monoamino-β-CD 3 were prepared according to literature.20 Synthetic procedures and spectral data of new compounds (1, 5, 9, 10, 12, 13 and 17), and experimental details of complexation study are described in Supporting Information.

Measurements

The frequency dependence of the oscillatory shear moduli, such as shear storage modulus G′ and loss modulus G″ in aqueous solutions, was measured by a cone-and-plate rheometer (MR500, UBM, Kyoto, Japan) at 25±1 °C. The cone angle was 5° and the diameter was 25 mm.

X-ray diffraction measurement was performed with a powder diffractometer (RINT2000, Rigaku, Tokyo, Japan) using graphite-monochromatized CuKα radiation (λ=1.542 ).

Matrix-assisted laser desorption/ionization time-of-flight mass spectra were recorded in the reflector mode on a mass spectrometer (Voyager DE RP, PerSeptive Biosystems, Framingham, MA, USA) using a nitrogen laser (337 nm) and an accelerating potential of 25 kV. α-Cyano-4-hydroxycinnamic acid was used as a matrix.

Results and discussion

Preparation of dumbbell-shaped PEG chains 1 and supramolecular crosslinkers, ditopic 4 and tetratopic 5

The dumbbell-shaped PEG chains 1ae were prepared by a reaction of PEG (average n=22) bis(2-aminoethyl) ether with corresponding benzoyl chlorides 6 that have one or two alkyloxy group(s) at 2-, 4- or 6-position (Scheme 2). The ditopic crosslinker 4 was prepared by attachment of monoaminated permethylated β-CD to each end of PEG (average l=7) bis(carboxymethyl) ether through a condensation reaction.17 The tetratopic crosslinker 5 was prepared by repeated 1,3-dipolar cycloaddition reactions23, 24 of monoazidated permethylated β-CD 820 and quadruply-azidated pentaerythritol ethoxylate 10 (average a+b+c+d=15) at the respective ends of PEG (average m=9) bis(prop-2-ynyl) ether 7 (Scheme 3).

Inclusion complexation of dumbbell-shaped 1 with β-CD 2

Complexation of the dumbbell-shaped PEG chains 1 with native β-CD 2 was first investigated by mixing in water at room temperature and at 60 °C (Scheme 4 and Table 1). Mixing of 1a with 2 in water at room temperature for 10 days successfully gave a white solid. The 1H nuclear magnetic resonance spectrum of the isolated solid measured in DMSO-d6 indicated a simple integration of 1a and 2 at a ratio of 1 to 10. An indistinguishable solid was given on mixing at 60 °C from the solid formed at room temperature. The powder X-ray diffraction pattern for the solid of 1a and 2 is quite similar to that of β-CD itself.4, 25 Mixing of 1a with permethylated 3 failed to produce any solid, and just gave a transparent solution at both room temperature and 60 °C. If we consider the hydrophobic inherence in 1a, whose solution is turbid in water at any temperature, the solubilization would be accounted for by assuming inclusion complexation with 3 at least at the end of 1a.17 It would be difficult to judge whether the methylated β-CD was trapped onto 1a or not from only the appearance due to high water solubility of 3.18 Similar results were obtained from mixing of 1b with 2 or 3 qualitatively, in terms of precipitation or solubilization (Table 1). Note that mixing at 60 °C accelerated precipitation,7 and gave an indistinguishable solid in a similar yield to that given at room temperature. A longer time was required for precipitation that resulted in a higher yield for 1a [R2=OPr, R4=OBn] than for 1b [R2=OEt, R4=Obn] (Table 1). All solids obtained here dissolved in DMSO or in an excessive amount of water, indicating formation of hydrogen bonds as commonly seen in an inclusion complex of native cyclodextrins.1, 2, 3, 4, 26, 27 As previously reported, the results of mixing PEG bis(2-aminoethyl) ether, which has no bulkiness at the ends, with α-CD1, 2 and β-CD3, 4 are also listed in Table 1 for reference. As in the case of the mixing of 1a with 3, no precipitates were formed from a transparent solution of 1c [R2=OPr, R4=OPr], 1d [R2=OPr] or 1e [R2=OPr, R6=OPr] in the presence of 2 at any temperature (Scheme 4).

Table 1 Conditions (concentration and temperature) for complexation of 1a, 1b or PEGBA with 2, 3 or α-CD,a and results (time for precipitation, ratiob of PEG to CD in an isolated solid and yieldc)

Supramolecular crosslinking of dumbbell-shaped 1 with ditopic 4 and tetratopic 5

Complexation of dumbbell-shaped 1 with the ditopic crosslinker 4 was then investigated in terms of the zero-shear viscosity (η0) of a transparent solution in water under several conditions (Table 2). If each of the two permethylated β-CD molecules in 4 is discretely assembled onto a chain, and the supramolecularly crosslinked complexes are stable, this will lead to an increase in viscosity.28 Mixing of 1a/b (46 mM) with 4 (0.25 M) at room temperature for 10/5 days led to no change in viscosity (Figures 2a and b), but the solution appeared to be similar to a solution of 1a and permethylated 3. Alternatively, heating these systems induced increases in viscosity over time, which attained an order of 105 Pa•s after periods of 6 days for 1a [R2=OPr, R4=OBn], and 3 days for 1b [R2=OEt, R4=OBn] (Scheme 5 and Figures 2a and b). If the increase in viscosity was achieved through inclusion complexation with 4 only at the ends of 1a/b, the solution viscosity would decrease with heating.29, 30, 31, 32 It is noteworthy that a gradual increase in viscosity was also found in a solution of 1c (46 mM) [R2=OPr, R4=OPr] in the presence of 4 (0.24 M) at 40 °C (Scheme 5 and Figure 2c), if we consider the failure of precipitation to occur on mixing of 1c with native β-CD 2 at any temperature (Scheme 4). The viscosity did not increase at room temperature as in the case of mixing of 1a or 1b with 4 (Figure 2). Also note that these increased viscosities still remained for weeks after the system cooled down, and returned to solutions with low viscosity (10−2 Pa•s) by triple dilution with water followed by shaking at room temperature for 5 days for 1a, for 2 days for 1b and within 1 day for 1c (Scheme 5). These results indicate that the pseudopolyrotaxanes were formed on heating,18 and were kinetically stable during the supramolecular crosslinking. It is important for the system to be heated to form an assembly through the supramolecular crosslinking, although slipping on/off is allowed even at room temperature (see above). The values of η0 measured at low concentrations ([1ac]<20 mM, [4]<0.10 M) were on the order of 100 Pa•s. The values increased with concentration as follows: η0=2.1 × 103 Pa•s for 1a and 4, and 1.9 × 102 Pa•s for 1b and 4 ([1a], [1b]=31 mM, [4]=0.16 M) and so on, measured after maintaining a solution at 40 °C for 8 days. Solutions with so high concentrations are no longer allowed to measure nuclear magnetic resonance with suitable quality. In a transparent solution of 1d, 1e or PEG bis(2-aminoethyl) ether in the presence of 4, the viscosity remained on an order of 10−2 Pa•s under any conditions (Scheme 5). These results are also summarized in Table 2.

Table 2 Conditions (concentration,a temperature and time) for mixing of 1ae or PEGBA with 4 or 5, and zero-shear viscosity
Figure 2
figure2

Zero-shear viscosities (η0) of aqueous solution of (a) dumbbell-shaped PEG 1a, (b) 1b and (c) 1c (46 mM) in the presence of ditopic crosslinker 4 (0.25 M), determined by measurement of complex viscosities (η*) at 25±1 °C, followed by calculation according to the equation η0≡limω → 0(G″/ω). For a solution of 1b stirred at 40 °C for 6 days (Figure 2b), the viscosity was not determined due to disappearance of the terminal region.

A solution with increased viscosity becomes harder to stir. In fact, a stirring bar stopped on the 8th/6th day from the time a solution of 1a/b and 4 was heated to 40 °C, whereas it had been continuing in a solution of 1c and 4 for 8 days at that temperature. As shown in Figure 3, the solution of 1a and 4 appears deceptively something similar to a gel in the photograph (Figure 3a), and is fluent in the long term (2 days; Figure 3b). We describe these macroscopic observations through dynamic viscoelastic measurement.33 For the solution of 1a/b and 4 stirred at 40 °C for 8/6 days, we can find the rubbery region in high frequency, indicating that the solution property changed from viscous to elastic (Figures 4a and b). Alternatively, for the solution of 1c and 4, the terminal region was clearly detected (Figure 4c). Changes over time in the oscillatory shear moduli are summarized in Supplementary Figures S1–S3.

Figure 3
figure3

Photographs of aqueous solution of dumbbell-shaped poly(ethylene glycol) 1a (46 mM) and ditopic crosslinker 4 (0.25 M), stirred at 40 °C for 8 days, followed by inverting and standing for (a) 0 and (b) 24 h.

Figure 4
figure4

Frequency dependency of storage modulus (G′, red circle) and loss modulus (G″, blue square) of aqueous solution of (a) dumbbell-shaped poly(ethylene glycol) 1a in the presence of ditopic crosslinker 4 stirred at 40 °C for 8 days, (b) 1b in the presence of 4 stirred at 40 °C for 6 days and (c) 1c in the presence of 4 stirred at 40 °C for 8 days ([1]=46 mM, [4]=0.25 M), measured at 25±1 °C.

We found a remarkable change in the dynamic viscoelastic property when the tetratopic crosslinker 5 was used in complexation with 1a. In a solution of 1a (19 mM) and 5 (52 mM) stirred at 40 °C, a stirring bar stopped on the 3rd day. The frequency dependence of the oscillatory shear moduli showed plateaus at low frequency, and indicated that a network structure had formed in the transparent solution (Figure 5a).33 Once formed, returning to a low viscosity solution required a 7-day shaking after triple dilution. Replacing the tetratopic 5 with the ditopic 4 (0.10 M) in the above solution resulted in the value of η0 lying on the order of 100 Pa•s, although almost the same amount of permethylated β-CD was present in the solution (Table 2). In a solution of 1c (19 mM) and 5 (52 mM) stirred at 40 °C for 3 days, the terminal region was found (Figure 5b), which was not detected when the ditopic 4 (0.10 M) was used in place of 5 (Table 2).

Figure 5
figure5

Frequency dependency of storage modulus (G′, red circle) and loss modulus (G″, blue square) of aqueous solution of (a) dumbbell-shaped poly(ethylene glycol) 1a in the presence of tetratopic crosslinker 5, and (b) 1c in the presence of 5 stirred at 40 °C for 3 days ([1]=19 mM, [5]=52 mM), measured at 25±1 °C. In a solution of 1a/c (19 mM) itself or 5 (52 mM) itself, the values of G′ and G″ were on the order of 10−2 Pa, measured under the same conditions.

Conclusions

A series of dumbbell-shaped PEG chains 1 were designed and prepared to investigate systematically the role of barriers at the ends of 1 through the self-assembling of size-mismatched cyclic and linear components (pseudopolyrotaxane formation). Differences in chemical structure at the ends of a chain were projected on macroscopic behaviors: substituents on 2,4-positions (a, b or c) affected the rate and yield of precipitation in the complexation with native β-CD that forms hydrogen bonds, and the rates of assembly as well as dissociation in complexation with a ditopic/tetratopic supramolecular crosslinker 4/5 that kinetically stabilizes the assembly without relying on hydrogen bonds. In addition, the self-assembling of 1ac with 4/5 was induced only at 40 °C or higher, although a number of supramolecular assemblies dissociate on heating.1, 29, 30, 31, 32, 34, 35, 36, 37, 38 Substituent(s) on 2- or 2,6-positions (d or e) were too small or bulky to work well. The system was also well modulated by crosslinking of a cyclic component, as demonstrated by combinations of 1ac and monotopic 3/ditopic 4, or 1a/c and ditopic 4/tetratopic 5. A precise design of end groups according to a cyclic component would broaden the range of possibilities in selecting a chain without relying on a specific interaction between the components.

scheme1

(a) Pseudopolyrotaxane formation between size-matched cyclic and linear components, (b) pseudopolyrotaxane formation between size-mismatched cyclic and dumbbell-shaped linear components and (c) supramolecular crosslinking based on pseudopolyrotaxane formation between size-mismatched crosslinked cyclic and dumbbell-shaped linear components.

scheme2

Preparation of dumbbell-shaped poly(ethylene glycol) chains 1. PEGBA, poly(ethylene glycol) bis(2-aminoethyl) ether

scheme3

Preparation of tetratopic crosslinker 5.

scheme4

Mixing of 1 with 2 in water leading to precipitation (1a, 1b) at room temperature (r.t.) or elevated temperature, or no precipitation (1c, 1d and 1e), and dissociation by dilution.

scheme5

Mixing of 1 with 4 in water leading to increase in viscosity only at elevated temperature (1a, 1b and 1c) or no increase (1d, 1e), and dissociation by dilution.

References

  1. 1

    Harada, A. & Kamachi, M. Complex formation between poly(ethylene glycol) and α-cyclodextrin. Macromolecules 23, 2821–2823 (1990).

    CAS  Article  Google Scholar 

  2. 2

    Harada, A., Li, J. & Kamachi, M. Preparation and properties of inclusion complexes of polyethylene glycol with α-cyclodextrin. Macromolecules 26, 5698–5703 (1993).

    CAS  Article  Google Scholar 

  3. 3

    Harada, A. & Kamachi, M. Complex formation between cyclodextrin and poly(propylene glycol). J. Chem. Soc. Chem. Commun 19, 1322–1323 (1990).

    Article  Google Scholar 

  4. 4

    Harada, A., Okada, M., Li, L. & Kamachi, M. Preparation and characterization of inclusion complexes of poly(propylene glycol) with cyclodextrins. Macromolecules 28, 8406–8411 (1995).

    CAS  Article  Google Scholar 

  5. 5

    Nepogodiev, S. A. & Stoddart, J. F. Cyclodextrin-based catenanes and rotaxanes. Chem. Rev. 98, 1959–1976 (1998).

    CAS  Article  Google Scholar 

  6. 6

    Wenz, G., Han, B. H. & Müller, A. Cyclodextrin rotaxanes and polyrotaxanes. Chem. Rev. 106, 782–817 (2006).

    CAS  Article  Google Scholar 

  7. 7

    Wenz, G. Recognition of monomers and polymers. Adv. Polym. Sci. 222, 1–54 (2009), and references therein.

    CAS  Article  Google Scholar 

  8. 8

    Harada, A., Hashidzume, A., Yamaguchi, H. & Takashima, Y. Polymeric rotaxanes. Chem. Rev. 109, 5974–6023 (2009).

    CAS  Article  Google Scholar 

  9. 9

    Huang, F. & Gibson, H. W. Polypseudorotaxanes and polyrotaxanes. Prog. Polym. Sci. 30, 982–1018 (2005).

    CAS  Article  Google Scholar 

  10. 10

    Takata, T., Kihara, N. & Furusho, Y. Polyrotaxanes and polycatenanes: recent advances in syntheses and applications of polymers comprising of interlocked structures. Adv. Polym. Sci. 171, 1–76 (2004).

    CAS  Article  Google Scholar 

  11. 11

    Nakazono, K., Takashima, T., Arai, T., Koyama, Y. & Takata, T. High-yield one-pot synthesis of permethylated α-cyclodextrin-based polyrotaxane in hydrocarbon solvent through an efficient heterogeneous reaction. Macromolecules 43, 691–696 (2010).

    CAS  Article  Google Scholar 

  12. 12

    Arai, T., Hayashi, M., Takagi, N. & Takata, T. One-pot synthesis of native and permethylated α-cyclodextrin-containing polyrotaxanes in water. Macromolecules 42, 1881–1887 (2009).

    CAS  Article  Google Scholar 

  13. 13

    Li, J., Harada, A. & Kamachi, M. Sol–gel transition during inclusion complex formation between α-cyclodextrin and high molecular weight poly(ethylene glycol)s in aqueous solution. Polym. J. 26, 1019–1026 (1994).

    CAS  Article  Google Scholar 

  14. 14

    Gong, C. & Gibson, H. W. Supramolecular chemistry with macromolecules: macromolecular knitting, reversible formation of branched polyrotaxanes by self-assembly. Macromol. Chem. Phys. 199, 1801–1806 (1998).

    CAS  Article  Google Scholar 

  15. 15

    Sohgawa, Y. H., Fujimori, H., Shoji, J., Furusho, Y., Kihara, N. & Takata, T. Polyslipping: a new approach to polyrotaxane-like assemblies. Chem. Lett. 30, 774–775 (2001).

    Article  Google Scholar 

  16. 16

    Gibson, H. W., Yamaguchi, N. & Jones, J. W. Supramolecular pseudorotaxane polymers from complementary pairs of homoditopic molecules. J. Am. Chem. Soc. 125, 3522–3533 (2003).

    CAS  Article  Google Scholar 

  17. 17

    Katoono, R., Kobayashi, Y., Yamaguchi, M. & Yui, N. Heat-induced supramolecular crosslinking of dumbbell-shaped PEG with β-CD dimer based on reversible loose-fit rotaxanation. Macromol. Chem. Phys. 212, 211–215 (2011).

    CAS  Article  Google Scholar 

  18. 18

    Katoono, R., Kobayashi, Y. & Yui, N. Preparation of loose-fit polyrotaxane composed of β-cyclodextrin and poly(ethylene glycol) derivatives through the slipping–expanding protocol. Chem. Lett. 39, 892–893 (2010).

    CAS  Article  Google Scholar 

  19. 19

    Udachin, K. A., Wilson, L. D. & Ripmeester, J. A. Solid polyrotaxanes of polyethylene glycol and cyclodextrins: the single crystal X-ray structure of PEGβ-cyclodextrin. J. Am. Chem. Soc. 122, 12375–12376 (2000).

    CAS  Article  Google Scholar 

  20. 20

    Muderawan, I. W., Ong, T. T., Lee, T. C., Young, D. J., Ching, C. B. & Ng, S. C. A reliable synthesis of 2- and 6-amino-β-cyclodextrin and permethylated-β-cyclodextrin. Tetrahedron Lett. 46, 7905–7907 (2005).

    CAS  Article  Google Scholar 

  21. 21

    Zhang, G., Fang, L., Zhu, L., Sun, D. & Wang, P. G. Syntheses and biological activity of bisdaunorubicins. Bioorg. Med. Chem. 14, 426–434 (2006).

    CAS  Article  Google Scholar 

  22. 22

    Harada, A., Li, J. & Kamachi, M. Preparation and characterization of a polyrotaxane consisting of monodisperse poly(ethylene glycol) and α-cyclodextrins. J. Am. Chem. Soc. 116, 3192–3196 (1994).

    CAS  Article  Google Scholar 

  23. 23

    Rostovtsev, V. V., Green, L. G., Fokin, V. V. & Sharpless, K. B. A Stepwise huisgen cycloaddition process: copper(I)-catalyzed regioselective “ligation” of azides and terminal alkynes. Angew. Chem. Int. Ed. 41, 2596–2599 (2002).

    CAS  Article  Google Scholar 

  24. 24

    Rodionov, V. O., Fokin, V. V. & Finn, M. G. Mechanism of the ligand-free cui-catalyzed azide–alkyne cycloaddition reaction. Angew. Chem. Int. Ed. 44, 2210–2215 (2005).

    CAS  Article  Google Scholar 

  25. 25

    Saenger, W. Cyclodextrin inclusion compounds in research and industry. Angew. Chem. Int. Ed. 19, 344–362 (1980).

    Article  Google Scholar 

  26. 26

    Harada, A., Li, J., Suzuki, S. & Kamachi, M. Complex formation between polyisobutylene and cyclodextrins: inversion of chain-length selectivity between β-cyclodextrin and γ-cyclodextrin. Macromolecules 26, 5267–5268 (1993).

    CAS  Article  Google Scholar 

  27. 27

    Harada, A., Li, J. & Kamachi, M. The molecular necklace: a rotaxane containing many threaded α-cyclodextrins. Nature 356, 325–327 (1992).

    CAS  Article  Google Scholar 

  28. 28

    Ferry, J. D. Viscoelastic Properties of Polymers Ch. 11, 264–320 (John Wiley & Sons Inc., New York, 1980).

    Google Scholar 

  29. 29

    Sandier, A., Brown, W. & Mays, H. Interaction between an adamantane end-capped poly(ethylene oxide) and a β-cyclodextrin polymer. Langmuir 16, 1634–1642 (2000).

    CAS  Article  Google Scholar 

  30. 30

    van de Manakker, F., van der Pot, M., Vermonden, T., van Nostrum, C. F. & Hennink, W. E. Self-assembling hydrogels based on β-cyclodextrin/cholesterol inclusion complexes. Macromolecules 41, 1766–1773 (2008).

    CAS  Article  Google Scholar 

  31. 31

    Herbst, F., Schröter, K., Gunkel, I., Gröger, S., Albrecht, T. T., Balbach, J. H. & Binder, W. Aggregation and chain dynamics in supramolecular polymers by dynamic rheology: cluster formation and self-aggregation. Macromolecules 43, 10006–10016 (2010).

    CAS  Article  Google Scholar 

  32. 32

    Dingenouts, N., Klyatskaya, S., Rosenfeldt, S., Ballauff, M. & Höger, S. Temperature-induced switching between aggregated and nonaggregated states in coilringcoil block copolymers. Macromolecules 42, 5900–5902 (2009).

    CAS  Article  Google Scholar 

  33. 33

    Larson, R. G. The Structure and Rheology of Complex Fluids (ed. Gubbins, K.E.) Ch. 5, 232–260 (Oxford University Press, New York, 1999).

    Google Scholar 

  34. 34

    Brunsveld, L., Folmer, B. J. B., Meijer, E. W. & Sijbesma, R. P. Supramolecular polymers. Chem. Rev. 101, 4071–4097 (2001).

    CAS  Article  Google Scholar 

  35. 35

    Borzsonyi, G., Beingessner, R. L., Yamazaki, T., Cho, J. Y., Myles, A. J., Malac, M., Egerton, R., Kawasaki, M., Ishizuka, K., Kovalenko, A. & Fenniri, H. Water-soluble J-type rosette nanotubes with giant molar ellipticity. J. Am. Chem. Soc. 132, 15136–15139 (2010).

    CAS  Article  Google Scholar 

  36. 36

    Nieuwenhuizen, M. M. L., de Greef, T. F. A., van der Bruggen, R. L. J., Paulusse, J. M. J., Appel, W. P. J., Smulders, M. M. J., Sijbesma, R. P. & Meijer, E. W. Self-assembly of ureido-pyrimidinone dimers into one-dimensional stacks by lateral hydrogen bonding. Chem. Eur. J. 16, 1601–1612 (2010).

    CAS  Article  Google Scholar 

  37. 37

    George, S. J. & Ajayaghosh, A. Self-assembled nanotapes of oligo(p-phenylene vinylene)s: sol–gel-controlled optical properties in fluorescent π-electronic gels. Chem. Eur. J. 11, 3217–3227 (2005).

    CAS  Article  Google Scholar 

  38. 38

    Ikeda, M., Nobori, T., Schmutz, M. & Lehn, J. M. Hierarchical self-assembly of a bow-shaped molecule bearing self-complementary hydrogen bonding sites into extended supramolecular assemblies. Chem. Eur. J. 11, 662–668 (2005).

    CAS  Article  Google Scholar 

Download references

Acknowledgements

We thank Associate Professor Akio Ohta (Kanazawa University) and Dr Issey Osaka (JAIST) for their help in characterization (elemental analysis and mass spectrometry) of the new compounds.

Author information

Affiliations

Authors

Corresponding author

Correspondence to Ryo Katoono.

Additional information

Supplementary Information accompanies the paper on Polymer Journal website

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Kobayashi, Y., Katoono, R., Yamaguchi, M. et al. Modulation of reversible self-assembling of dumbbell-shaped poly(ethylene glycol)s and β-cyclodextrins: precipitation and heat-induced supramolecular crosslinking. Polym J 43, 893–900 (2011). https://doi.org/10.1038/pj.2011.71

Download citation

Keywords

  • β-cyclodextrin
  • poly(ethylene glycol)
  • pseudopolyrotaxane
  • supramolecular crosslinking
  • viscoelastic properties
  • viscosity

Further reading

Search