Self-recoverable semi-crystalline hydrogels with thermomechanics and shape memory performance

More info
  • ReceivedJul 18, 2018
  • AcceptedAug 31, 2018
  • PublishedSep 21, 2018


Stimuli-responsive hydrogels have become one of the most popular artificial soft materials due to their excellent adaption to complex environments. Thermoresponsive hydrogels triggered by temperature change can be efficiently utilized in many applications. However, these thermoresponsive hydrogels mostly cannot recover their mechanical states under large strain during the process. Herein, we utilize the heterogeneous comb-type polymer network with semi-crystalline hydrophobic side chains to design self-recovery semi-crystalline hydrogels. Based on hydrophilic/hydrophobic cooperative complementary interaction and heterogeneous polymer network, hydrogels can be endowed with excellent thermosensitive properties and mechanical performance. The hydrogels exhibit high compressive strength (7.57 MPa) and compressive modulus (1.76 MPa) due to the semi-crystalline domains formed by association of the hydrophobic poly(ε-caprolactone) PCL. The melting-crystalline transition of PCL and elastic polymer network provide the hydrogels excellent thermomechanical performance and self-recovery property. Furthermore, the hydrogels exhibit shape memory behavior, which can be realized by simple process and smart surface patterning. With these excellent properties, our hydrogels can be applied in sensors, flexible devices and scaffolds for tissue engineering.

Funded by

the National Natural Science Foundation of China(21574004)

the National Natural Science Funds for Distinguished Young Scholar(21725401)

the Fundamental Research Funds for the Central Universities

the National ‘Young Thousand Talents Program’

and the China Postdoctoral Science Foundation(2017M620012)


This work was financially supported by the National Natural Science Foundation of China (21574004), the National Natural Science Funds for Distinguished Young Scholar (21725401), the Fundamental Research Funds for the Central Universities, the National ‘Young Thousand Talents Program’, and the China Postdoctoral Science Foundation (2017M620012).

Interest statement

The authors declare that they have no conflict of interest.

Contributions statement

Zhang K, Zhao Z and Liu M designed the project. Zhang K and Huang J preformed the experiments. Zhang K, Zhao Z, Zhao T and Fang R analyzed the results. Zhang K, Fang R and Liu M wrote the paper. All authors contributed to general discussion of the article

Author information

Kangjun Zhang received his BSc degree from Beihang University in 2016. He is now a master candidate under the supervision of Prof. Mingjie Liu at Beihang University. His research focuses on the fabrication of smart hydrogels based on cooperative complementary interaction.

Ruochen Fang is a post-doctor in Beihang University. In 2011, He received his BSc degree in polymer materials and engineering in the Department of Chemistry from Jilin University. Then he joined Prof. Xi Zhang’s group and received his PhD degree from Tsinghua University in 2016. His current research interest focuses on binary cooperative complementary nanomaterials and bioinspired material science.

Mingjie Liu is currently a full-time professor at Beihang University. In 2005, he joined Prof. Lei Jiang’s group and received his PhD degree from the National Center for Nanoscience and Technology, Chinese Academy of Sciences (2010). He then worked as a postdoc in Prof. Takuzo Aida’s group in Riken in Japan from 2010 to 2015. In 2015, he was awarded the “1000 Youth Plan program” and joined Beihang University. In 2017, he was awarded the National Science Fund for Distinguished Young Scholars. His current research interest focuses on anisotropic soft matter with ordered structures, bioinspired design, and application of gel materials.


Supplementary information

Experimental details and supporting data are available in the online version of the paper.


[1] Zhao ZG, Xu YC, Fang RC, et al. Bioinspired adaptive gel materials with synergistic heterostructures. Chin J Polym Sci, 2018, 36: 683-696 CrossRef Google Scholar

[2] Zhao Z, Fang R, Rong Q, et al. Bioinspired nanocomposite hydrogels with highly ordered structures. Adv Mater, 2017, 29: 1703045 CrossRef PubMed Google Scholar

[3] Chen L, Yin Y, Liu Y, et al. Design and fabrication of functional hydrogels through interfacial engineering. Chin J Polym Sci, 2017, 35: 1181-1193 CrossRef Google Scholar

[4] Zhang Y, Liao J, Wang T, et al. Polyampholyte hydrogels with pH modulated shape memory and spontaneous actuation. Adv Funct Mater, 2018, 28: 1707245 CrossRef Google Scholar

[5] Kim YS, Liu M, Ishida Y, et al. Thermoresponsive actuation enabled by permittivity switching in an electrostatically anisotropic hydrogel. Nat Mater, 2015, 14: 1002-1007 CrossRef PubMed ADS Google Scholar

[6] Lu W, Le X, Zhang J, et al. Supramolecular shape memory hydrogels: a new bridge between stimuli-responsive polymers and supramolecular chemistry. Chem Soc Rev, 2017, 46: 1284-1294 CrossRef PubMed Google Scholar

[7] Le X, Lu W, Zheng J, et al. Stretchable supramolecular hydrogels with triple shape memory effect. Chem Sci, 2016, 7: 6715-6720 CrossRef PubMed Google Scholar

[8] Li Z, Lu W, Ngai T, et al. Mussel-inspired multifunctional supramolecular hydrogels with self-healing, shape memory and adhesive properties. Polym Chem, 2016, 7: 5343-5346 CrossRef Google Scholar

[9] Wang W, Fan X, Li F, et al. Magnetochromic photonic hydrogel for an alternating magnetic field-responsive color display. Adv Opt Mater, 2018, 6: 1701093 CrossRef Google Scholar

[10] Shim TS, Kim SH, Sim JY, et al. Dynamic modulation of photonic bandgaps in crystalline colloidal arrays under electric field. Adv Mater, 2010, 22: 4494-4498 CrossRef PubMed Google Scholar

[11] Klouda L, Mikos AG. Thermoresponsive hydrogels in biomedical applications. Eur J Pharm BioPharm, 2008, 68: 34-45 CrossRef PubMed Google Scholar

[12] Gao F, Zhang Y, Li Y, et al. Sea cucumber-inspired autolytic hydrogels exhibiting tunable high mechanical performances, repairability, and reusability. ACS Appl Mater Interfaces, 2016, 8: 8956-8966 CrossRef Google Scholar

[13] Hu Y, Kahn JS, Guo W, et al. Reversible modulation of DNA-based hydrogel shapes by internal stress interactions. J Am Chem Soc, 2016, 138: 16112-16119 CrossRef PubMed Google Scholar

[14] Dong LC, Yan Q, Hoffman AS. Controlled release of amylase from a thermal and pH-sensitive, macroporous hydrogel. J Control Release, 1992, 19: 171-177 CrossRef Google Scholar

[15] Zhang XZ, Yang YY, Chung TS, et al. Preparation and characterization of fast response macroporous poly(N-isopropylacrylamide) hydrogels. Langmuir, 2001, 17: 6094-6099 CrossRef Google Scholar

[16] Rong Q, Lei W, Chen L, et al. Anti-freezing, conductive self-healing organohydrogels with stable strain-sensitivity at subzero temperatures. Angew Chem Int Ed, 2017, 56: 14159-14163 CrossRef PubMed Google Scholar

[17] Luo F, Sun TL, Nakajima T, et al. Oppositely charged polyelectrolytes form tough, self-healing, and rebuildable hydrogels. Adv Mater, 2015, 27: 2722-2727 CrossRef PubMed Google Scholar

[18] Zhang HJ, Sun TL, Zhang AK, et al. Tough physical double-network hydrogels based on amphiphilic triblock copolymers. Adv Mater, 2016, 28: 4884-4890 CrossRef PubMed Google Scholar

[19] Zhao Z, Zhang K, Liu Y, et al. Highly stretchable, shape memory organohydrogels using phase-transition microinclusions. Adv Mater, 2017, 29: 1701695 CrossRef PubMed Google Scholar

[20] Dai X, Zhang Y, Gao L, et al. A mechanically strong, highly stable, thermoplastic, and self-healable supramolecular polymer hydrogel. Adv Mater, 2015, 27: 3566-3571 CrossRef PubMed Google Scholar

[21] Zhang Y, Li Y, Liu W. Dipole-dipole and H-bonding interactions significantly enhance the multifaceted mechanical properties of thermoresponsive shape memory hydrogels. Adv Funct Mater, 2015, 25: 471-480 CrossRef Google Scholar

[22] Liu M, Jiang L. Dialectics of nature in materials science: binary cooperative complementary materials. Sci China Mater, 2016, 59: 239-246 CrossRef Google Scholar

[23] Zhao Z, Liu Y, Zhang K, et al. Biphasic synergistic gel materials with switchable mechanics and self-healing capacity. Angew Chem, 2017, 129: 13649-13654 CrossRef Google Scholar

[24] Gao H, Zhao Z, Cai Y, et al. Adaptive and freeze-tolerant heteronetwork organohydrogels with enhanced mechanical stability over a wide temperature range. Nat Commun, 2017, 8: 15911 CrossRef PubMed ADS Google Scholar

[25] Abdurrahmanoglu S, Can V, Okay O. Design of high-toughness polyacrylamide hydrogels by hydrophobic modification. Polymer, 2009, 50: 5449-5455 CrossRef Google Scholar

[26] Tuncaboylu DC, Argun Aı, Sahin M, et al. Structure optimization of self-healing hydrogels formed via hydrophobic interactions. Polymer, 2012, 53: 5513-5522 CrossRef Google Scholar

[27] Bilici C, Ide S, Okay O. Yielding behavior of tough semicrystalline hydrogels. Macromolecules, 2017, 50: 3647-3654 CrossRef ADS Google Scholar

[28] Zhang Z, Ni J, Chen L, et al. Biodegradable and thermoreversible PCLA–PEG–PCLA hydrogel as a barrier for prevention of post-operative adhesion. Biomaterials, 2011, 32: 4725-4736 CrossRef PubMed Google Scholar

[29] Yu L, Zhang H, Ding J. A subtle end-group effect on macroscopic physical gelation of triblock copolymer aqueous solutions. Angew Chem Int Ed, 2006, 45: 2232-2235 CrossRef PubMed Google Scholar

[30] Chen L, Ci T, Yu L, et al. Effects of molecular weight and its distribution of PEG block on micellization and thermogellability of PLGA–PEG–PLGA copolymer aqueous solutions. Macromolecules, 2015, 48: 3662-3671 CrossRef ADS Google Scholar

[31] Chen L, Li X, Cao L, et al. An injectable hydrogel with or without drugs for prevention of epidural scar adhesion after laminectomy in rats. Chin J Polym Sci, 2016, 34: 147-163 CrossRef Google Scholar

[32] Cui SQ, Yu L, Ding JD. Injectable thermogels based on block copolymers of appropriate amphiphilicity. Acta Polym Sin, 2018: 997–1015. Google Scholar

[33] Bellin I, Kelch S, Langer R, et al. Polymeric triple-shape materials. Proc Natl Acad Sci USA, 2006, 103: 18043-18047 CrossRef PubMed ADS Google Scholar

[34] Lendlein A, Langer R. Biodegradable, elastic shape-memory polymers for potential biomedical applications. Science, 2002, 296: 1673-1676 CrossRef PubMed ADS Google Scholar

[35] Huang M, Zhao K, Wang L, et al. Dual stimuli-responsive polymer prodrugs quantitatively loaded by nanoparticles for enhanced cellular internalization and triggered drug release. ACS Appl Mater Interfaces, 2016, 8: 11226-11236 CrossRef Google Scholar

[36] Yang CS, Wu HC, Sun JS, et al. Thermo-induced shape-memory PEG-PCL copolymer as a dual-drug-eluting biodegradable stent. ACS Appl Mater Interfaces, 2013, 5: 10985-10994 CrossRef PubMed Google Scholar

[37] Teubner M, Strey R. Origin of the scattering peak in microemulsions. J Chem Phys, 1987, 87: 3195-3200 CrossRef ADS Google Scholar

[38] Peng S, Guo Q, Hughes TC, et al. In situ synchrotron SAXS study of polymerizable microemulsions. Macromolecules, 2011, 44: 3007-3015 CrossRef ADS Google Scholar

[39] Wu G, Ying Q, Chu B. Lamellar structure of block copolymer poly(oxyethylene-oxypropylene-oxyethylene) in xylene/water mixtures. Macromolecules, 1994, 27: 5758-5765 CrossRef ADS Google Scholar

[40] Washburn NR, Lodge TP, Bates FS. Ternary polymer blends as model surfactant systems. J Phys Chem B, 2000, 104: 6987-6997 CrossRef Google Scholar

[41] Cao H, Chang X, Mao H, et al. Stereocomplexed physical hydrogels with high strength and tunable crystallizability. Soft Matter, 2017, 13: 8502-8510 CrossRef PubMed ADS Google Scholar

[42] Guo H, Mussault C, Brûlet A, et al. Thermoresponsive toughening in LCST-type hydrogels with opposite topology: from structure to fracture properties. Macromolecules, 2016, 49: 4295-4306 CrossRef ADS Google Scholar

  • Figure 1

    Preparation of SCHs. (a) Molecular structure of DMA, MEA and PCL-MA. (b) Schematic illustration of SCHs prepared by UV light polymerization and subsequently swelling. (c) The photos of precursor solution, polymer networks and SCHs. (d) The fitting of SAXS data of SCH2.5-6000 by T-S model. (e) SAXS profiles of SCHs with different PCL contents.

  • Figure 2

    Mechanical properties of SCHs. (a) Compressive strain-stress curves of hydrogel and SCHs with different PCL molecular weights. (b) Compressive strain-stress curves of hydrogel and SCHs with different PCL contents. (c, d) Compressive modulus of hydrogel, SCHs with different molecular weights and SCHs with different PCL contents, respectively.

  • Figure 3

    Thermomechanical properties of SCHs. (a) Compressive strain-stress curves of SCH2.5-6000 at different temperature. (b) Compressive modulus of SCHs with different molecular weights. (c) Compressive modulus of SCHs with different PCL contents. (d, e) The storage moduli (Gʹ) of the SCHs with different PCL molecular weights and contents at a frequency (ω) sweep of 15.8 rad s−1 and a constant shear strain (γ) of 0.5% by increasing temperature. (f) The storage moduli (Gʹ) of the SCH2.5-6000 in a temperature circulating test.

  • Figure 4

    Self-recovery performance of SCHs. (a) The loading-unloading curves of the SCH2.5-4000 with different compressive strains at 20°C. (b) The cyclic loading-unloading compressive tests of SCH2.5-4000 at 20°C. (c) The loading-unloading compressive tests of SCH2.5-4000 at 20 and 70°C. (d) The cyclic loading-unloading compressive tests of SCH2.5-4000 at 20°C with recovered by heat.

  • Figure 5

    Shape memory behaviors of SCHs. (a) Schematic illustration of the shape memory behavior of SCHs in the process of deforming, fixing and recovering. (b) Schematic illustration of internal structure of the PCL domains in the shape memory process. (c) Images showing the shape memory effects of SCHs. (d) The surface microstructure embossing and erasing during the shape memory process. The scale bar is 1 mm. (e) DSC thermograms exhibiting the melting (Tm=58.9°C) and crystallization temperature (Tc=21.5°C) of SCHs samples. (f) Shape memory behavior of compression and recovery. The black arrows indicate the four stages: (1) compressing at 70°C; (2) cooling to 20°C; (3) uploaded; and (4) heating to 70°C. (g) The fixed ratios and recovery ratios of SCHs with different molecular weights. (h) The fixed ratios and recovery ratios of SCHs with different PCL contents.

Copyright 2020  CHINA SCIENCE PUBLISHING & MEDIA LTD.  中国科技出版传媒股份有限公司  版权所有

京ICP备14028887号-23       京公网安备11010102003388号