Facile Synthesis of Functional Poly(ε-caprolactone) via Janus Polymerization

  • Huan Qiu
  • Zhe-Ning Yang
  • Jun LingEmail author


Functionalized aliphatic polyesters attract increasing attentions as biocompatible and biodegradable polymers with broad applications in biological science. In this contribution, we propose a facile and controllable synthetic technique for functional poly(ε- caprolactone) (PCL) via Janus polymerization, which comprises cationic ring-opening copolymerization (ROP) of ε-caprolactone (CL) with 3,3-bis(chloromethyl) oxacyclobutane (CO) and (coordinated) anionic ROP of CL at a single propagating chain by rare earth metal triflates (RE(OTf)3) and propylene oxide, thus generating block copolymers in one step. The compositions of the copolymers of poly(CLb-( CL-r-CO)) can be modulated by various RE(OTf)3. Scandium triflate catalyzes Janus polymerization to yield the copolymers containing the highest CO contents among all the RE(OTf)3 catalysts used with complete conversion of CL. The chlorine in CO repeating units is ready to be transferred into azide group which affords the modification sites to react with 9-ethynyl-9-fluorenol and mPEG-alkyne, respectively, via copper(I)-catalyzed azide-alkyne cycloaddition reaction with quantitative conversions of azides, as confirmed by FTIR analyses. According to NMR and SEC analyses, copolymers (PCC-g-PEG) bearing a homo-PCL block and a PEG-grafted block of poly(CO-co-CL) demonstrate well-defined chemical structures. The investigations on thermal properties reveal the strong phase separation between PCL and PEG blocks. The amphiphilic PCC-g-PEG is able to self-assemble into micelles in aqueous solution while cylindrical and lamellar morphologies are observed in bulk. We provide an efficient protocol to synthesize functional PCL combining onestep Janus polymerization and precise post-polymerization click reaction.


Janus polymerization Functional poly(ε-caprolactone) Poly(3,3-bis(chloromethyl) oxacyclobutane) Ring-opening polymerization Rare earth metal catalysts 


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This work was financially supported by the National Natural Science Foundation of China (No. 21871232) and Zhejiang Provincial Natural Science Foundation of China (No. LR15B040001).

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Facile Synthesis of Functional Poly(ε-caprolactone) via Janus Polymerization


  1. 1.
    Bednarek, M. Branched aliphatic polyesters by ring-opening (co)polymerization. Prog. Polym. Sci. 2016, 27–58.Google Scholar
  2. 2.
    Seyednejad, H.; Ghassemi, A. H.; Nostrum, C. F. V.; Vermonden, T.; Hennink, W. E. Functional aliphatic polyesters for biomedical and pharmaceutical applications. J. Control. Release 2011, 152, 168–176.CrossRefGoogle Scholar
  3. 3.
    Zhu, N.; Huang, W.; Hu, X.; Liu, Y.; Fang, Z.; Guo, K. Enzymatic continuous flow synthesis of thiol-terminated poly(d- valerolactone) and block copolymers. Macromol. Rapid Commun. 2018, 39, 1700807.CrossRefGoogle Scholar
  4. 4.
    Hajiali, F.; Tajbakhsh, S.; Shojaei, A. Fabrication and properties of polycaprolactone composites containing calcium phosphate- based ceramics and bioactive glasses in bone tissue engineering: A review. Polym. Rev. 2018, 58, 164–207.CrossRefGoogle Scholar
  5. 5.
    Dash, T. K.; Konkimalla, V. B. Polymeric modification and its implication in drug delivery: Poly-e-caprolactone (PCL) as a model polymer. Mol. Pharmaceut. 2012, 9, 2365–2379.CrossRefGoogle Scholar
  6. 6.
    Wang, J.; Wang, G.; Shan, H.; Wang, X.; Wang, C.; Zhuang, X.; Ding, J.; Chen, X. Gradiently degraded electrospun polyester scaffolds with cytostatic for urothelial carcinoma therapy. Biomater. Sci. 2019.Google Scholar
  7. 7.
    Chang, L.; Deng, L.; Wang, W.; Lv, Z.; Hu, F.; Dong, A.; Zhang, J. Poly(ethyleneglycol)-b-poly(e-caprolactone-co-?-hydroxyl- e-caprolactone) bearing pendant hydroxyl groups as nanocarriers for doxorubicin delivery. Biomacromolecules 2012, 13, 3301–3310.CrossRefGoogle Scholar
  8. 8.
    Habnouni, S. E.; Darcos, V.; Coudane, J. Synthesis and ring opening polymerization of a new functional lactone, a-iodo-e- caprolactone: A novel route to functionalized aliphatic polyesters. Macromol. Rapid Commun. 2009, 30, 165–169.CrossRefGoogle Scholar
  9. 9.
    Yan, J.; Zhang, Y.; Xiao, Y.; Zhang, Y.; Lang, M. Novel poly(e-caprolactone)s bearing amino groups: Synthesis, characterization and biotinylation. React. Funct. Polym. 2010, 70, 400–407.CrossRefGoogle Scholar
  10. 10.
    Ponsart, S.; Coudane, J.; Vert, M. A novel route to poly(e- caprolactone)-based copolymers via anionic derivatization. Biomacromolecules 2000, 1, 275–281.CrossRefGoogle Scholar
  11. 11.
    You, L.; Ling, J. Janus polymerization. Macromolecules 2014, 47, 2219–2225.CrossRefGoogle Scholar
  12. 12.
    Offenloch, J. T.; Mutlu, H.; Barner-Kowollik, C. Interrupted CuAAC ligation: An effcient approach to fluorescence labeled three-armed mikto star polymers. Macromolecules 2018, 51, 2682–2689.CrossRefGoogle Scholar
  13. 13.
    Zhao, W.; Wang, Y.; Liu, X.; Chen, X.; Cui, D.; Chen, E. Y. X. Protic compound mediated living cross-chain-transfer polymerization of rac-lactide: Synthesis of isotactic (crystalline)-heterotactic (amorphous) stereomultiblock polylactide. Chem. Commun. 2012, 48, 6375–6377.CrossRefGoogle Scholar
  14. 14.
    Zhao, W.; Wang, Y.; Liu, X.; Chen, X.; Cui, D. Synthesis of isotactic-heterotactic stereoblock (hard-soft) poly(lactide) with tacticity control through immortal coordination polymerization. Chem-Asian J. 2012, 7, 2403–2410.CrossRefGoogle Scholar
  15. 15.
    Tao, X.; Deng, Y.; Shen, Z.; Ling, J. Controlled polymerization of N-substituted glycine N-thiocarboxyanhydrides initiated by rare earth borohydrides toward hydrophilic and hydrophobic polypeptoids. Macromolecules 2014, 47, 6173–6180.CrossRefGoogle Scholar
  16. 16.
    You, L.; Hogen-Esch, T. E.; Zhu, Y.; Ling, J.; Shen, Z. Brønsted acid-free controlled polymerization of tetrahydrofuran catalyzed by recyclable rare earth triflates in the presence of epoxides. Polymer 2012, 53, 4112–4118.CrossRefGoogle Scholar
  17. 17.
    You, L.; Shen, Z.; Kong, J.; Ling, J. A novel approach to REOR bond from in situ reaction of rare earth triflates and sodium alkoxides: A versatile catalyst for living ring-opening polymerization of e-caprolactone. Polymer 2014, 55, 2404–2410.CrossRefGoogle Scholar
  18. 18.
    Li, Y.; Bai, T.; Li, Y.; Ling, J. Branched polytetrahydrofuran and poly(tetrahydrofuran-co-e-caprolactone) synthesized by Janus polymerization: A novel self-healing material. Macromol. Chem. Phys. 2017, 1600450.Google Scholar
  19. 19.
    Li, Y.; Luhe, M. V. D.; Schacher, F. H.; Ling, J. 3-Miktoarm star terpolymers via Janus polymerization: One-step synthesis and self-assembly. Macromolecules 2018, 51, 4938–4944.CrossRefGoogle Scholar
  20. 20.
    Wang, Y. Y.; Li, W.; Dai, L. Y. Cationic ring-opening polymerization of 3,3-bis(chloromethyl)oxacyclobutane in ionic liquids. Chin. Chem. Lett. 2007, 18, 1187–1190.CrossRefGoogle Scholar
  21. 21.
    Qiu, H.; Yang, Z.; Shah, M. I.; Mao, Z.; Ling, J. [PCL-b-(THFco- CL)]m multiblock copolymer synthesized by Janus polymerization. Polymer 2017, 128, 71–77.CrossRefGoogle Scholar
  22. 22.
    Shah, M. I.; Yang, Z.; Li, Y.; Jiang, L.; Ling, J. Properties of electrospun nanofibers of multi-block copolymers of [poly-e- caprolactone-b-poly(tetrahydrofuran-co-e-caprolactone)]m synthesized by Janus polymerization. Polymers 2017, 9, 559–568.CrossRefGoogle Scholar
  23. 23.
    Mukhametshin, T. I.; Petrov, A. I.; Kuznetsova, N. V.; Petrov, V. A.; Averianova, N. V.; Garaev, I. K.; Kostochko, A. V.; Gubaidullin, A. T.; Vinogradov, D. B.; Bulatov, P. V. Synthesis and copolymerization of azidomethyl-substituted oxetanes: The morphology of statistical block copolymers. Chemistry of Heterocyclic Compounds 2017, 53, 811–821.CrossRefGoogle Scholar
  24. 24.
    Leophairatana, P.; Silva, C. C. D.; Koberstein, J. T. How good is CuAAC 'click' chemistry for polymer coupling reactions? J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 75–84.CrossRefGoogle Scholar
  25. 25.
    Ban, Q.; Zhuang, Q.; Su, K.; Wu, S.; Kong, J. Interfacial liquid phase-driven removal of copper ions for bioavailable hyperbranched polytriazoles. J. Mater. Sci. 2018, 53, 10013–10024.CrossRefGoogle Scholar
  26. 26.
    Arslana, M.; Bicaka, T. C.; Pulidoc, B. A.; Nunescs, S. P.; Yagci, Y. Post modification of acetylene functional poly(oxindole biphenylylene) by photoinduced CuAAC. Eur. Polym. J. 2018, 100, 298–307.CrossRefGoogle Scholar
  27. 27.
    Yoshida, K.; Tanaka, S.; Yamamoto, T.; Tajima, K.; Borsali, R.; Isono, T.; Satoh, T. Chain-end functionalization with a saccharide for 10 nm microphase separation: 'Classical' PS-b- PMMA versus PS-b-PMMA-saccharide. Macromolecules 2018, 51, 8870–8877.CrossRefGoogle Scholar
  28. 28.
    He, W. N.; Xu, J. T.; Du, B. Y.; Fan, Z. Q.; Wang, X. Inorganic- salt-induced morphological transformation of semicrystalline micelles of PCL-b-PEO block copolymer in aqueous solution. Macromol. Chem. Phys. 2010, 211, 1909–1916.CrossRefGoogle Scholar
  29. 29.
    Saravanakumar, G.; Park, H.; Kim, J.; Park, D.; Pramanick, S.; Kim, D. H.; Kim, W. J. Miktoarm amphiphilic block copolymer with singlet oxygen-labile stereospecific ß-aminoacrylate junction: Synthesis, self-assembly, and photodynamically triggered drug release. Biomacromolecules 2018, 19, 2202–2213.CrossRefGoogle Scholar
  30. 30.
    Takeshita, H.; Fukumoto, K.; Ohnishi, T.; Ohkubo, T.; Miya, M.; Takenaka, K.; Shiomi, T. Formation of lamellar structure by competition in crystallization of both components for crystalline- crystalline block copolymers. Polymer 2006, 47, 8210–8218.CrossRefGoogle Scholar
  31. 31.
    Sun, Y. S.; Chung, T. M.; Li, Y. J.; Ho, R. M.; Ko, B. T.; Jeng, U. S.; Lotz, B. Crystalline polymers in nanoscale 1D spatial confinement. Macromolecules 2006, 39, 5782–5788.CrossRefGoogle Scholar
  32. 32.
    Sha, K.; Li, D.; Li, Y.; Zhang, B.; Wang, J. The chemoenzymatic synthesis of a novel CBABC-type pentablock copolymer and its self-assembled "crew-cut" aggregation. Macromolecules 2008, 41, 361–371.CrossRefGoogle Scholar
  33. 33.
    Xie, L. H.; Yin, C. R.; Lai, W. Y.; Fan, Q. L.; Huang, W. Polyfluorene- based semiconductors combined with various periodic table elements for organic electronics. Prog. Polym. Sci. 2012, 37, 1192–1264.CrossRefGoogle Scholar
  34. 34.
    Deng, C.; Yang, Z.; Zheng, Z.; Liu, N.; Ling, J. Photoluminescent nanoparticles in water with tunable emission for coating and ink-jet printing. J. Mater. Chem. C 2015, 3, 3666–3675.CrossRefGoogle Scholar
  35. 35.
    Tian, Y.; Chen, C. Y.; Yip, H. L.; Wu, W. C.; Chen, W. C.; Jen, A. K. Y. Synthesis, nanostructure, functionality, and application of polyfluorene-block-poly(N-isopropylacrylamide)s. Macromolecules 2010, 43, 282–291.CrossRefGoogle Scholar
  36. 36.
    Deng, C.; Jiang, P.; Shen, X.; Ling, J.; Hogen-Esch, T. E. White light emission of multi-chromophore photoluminescent nanoparticles using polyacrylate scaffold copolymers with pendent polyfluorene groups. Polym. Chem. 2014, 5, 5109–5115.CrossRefGoogle Scholar
  37. 37.
    Sriwichitkamol, K.; Suramitr, S.; Poolmee, P.; Hannongbua, S. Structures, absorption spectra, and electronic properties of polyfluorene and its derivatives: A theoretical study. J. Theor. Comput. Chem. 2006, 5, 595–608.CrossRefGoogle Scholar
  38. 38.
    Deng, C.; Ling, J. Amphiphilic copolymers of polyfluorene methacrylates exhibiting tunable emissions for ink-jet printing. Macromol. Rapid Commun. 2016, 37, 1352–1356.CrossRefGoogle Scholar

Copyright information

© Chinese Chemical Society Institute of Chemistry, Chinese Academy of Sciences Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and EngineeringZhejiang UniversityHangzhouChina

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