SCIENCE CHINA Technological Sciences, Volume 63 , Issue 7 : 1314-1322(2020) https://doi.org/10.1007/s11431-019-1498-y

Topological prime

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  • ReceivedNov 1, 2019
  • AcceptedDec 9, 2019
  • PublishedJan 14, 2020


Funded by

The work at Harvard was supported by NSF MRSEC(DMR-14-20570)


The work at Harvard was supported by National Science Foundation, Materials Research Science and Engineering Centers (Grant No. DMR-14-20570). Yang X X and Liu J J are visiting students at Harvard University supported by the China Scholarship Council.


Supporting Information

The supporting information is available online at tech.scichina.com and link.springer.com. The supporting materials are published as submitted, without typesetting or editing. The responsibility for scientific accuracy and content remains entirely with the authors.


[1] Gong J P. Why are double network hydrogels so tough? Soft Matter, 2010, 6: 2583–2590. Google Scholar

[2] Zhao X. Multi-scale multi-mechanism design of tough hydrogels: Building dissipation into stretchy networks. Soft Matter, 2014, 10: 672-687 CrossRef PubMed Google Scholar

[3] Long R, Hui C Y. Fracture toughness of hydrogels: Measurement and interpretation. Soft Matter, 2016, 12: 8069-8086 CrossRef PubMed Google Scholar

[4] Creton C, Ciccotti M. Fracture and adhesion of soft materials: A review. Rep Prog Phys, 2016, 79: 046601 CrossRef PubMed Google Scholar

[5] Bai R, Yang J, Suo Z. Fatigue of hydrogels. Eur J Mech-A/Solids, 2019, 74: 337-370 CrossRef Google Scholar

[6] Rowley J A, Madlambayan G, Mooney D J. Alginate hydrogels as synthetic extracellular matrix materials. Biomaterials, 1999, 20: 45-53 CrossRef Google Scholar

[7] Cheng H, Yue K, Kazemzadeh-Narbat M, et al. Mussel-inspired multifunctional hydrogel coating for prevention of infections and enhanced osteogenesis. ACS Appl Mater Interfaces, 2017, 9: 11428-11439 CrossRef Google Scholar

[8] Blacklow S O, Li J, Freedman B R, et al. Bioinspired mechanically active adhesive dressings to accelerate wound closure. Sci Adv, 2019, 5: eaaw3963 CrossRef PubMed Google Scholar

[9] Li J, Celiz A D, Yang J, et al. Tough adhesives for diverse wet surfaces. Science, 2017, 357: 378-381 CrossRef PubMed Google Scholar

[10] Faxälv L, Ekblad T, Liedberg B, et al. Blood compatibility of photografted hydrogel coatings. Acta Biomater, 2010, 6: 2599-2608 CrossRef PubMed Google Scholar

[11] Butruk B, Trzaskowski M, Ciach T. Fabrication of biocompatible hydrogel coatings for implantable medical devices using Fenton-type reaction. Mater Sci Eng-C, 2012, 32: 1601-1609 CrossRef PubMed Google Scholar

[12] Rogers J A, Someya T, Huang Y. Materials and mechanics for stretchable electronics. Science, 2010, 327: 1603-1607 CrossRef PubMed Google Scholar

[13] Chortos A, Liu J, Bao Z. Pursuing prosthetic electronic skin. Nat Mater, 2016, 15: 937-950 CrossRef PubMed Google Scholar

[14] Wirthl D, Pichler R, Drack M, et al. Instant tough bonding of hydrogels for soft machines and electronics. Sci Adv, 2017, 3: e1700053 CrossRef PubMed Google Scholar

[15] Yuk H, Lu B, Zhao X. Hydrogel bioelectronics. Chem Soc Rev, 2019, 48: 1642-1667 CrossRef PubMed Google Scholar

[16] Sheng H, Wang X, Kong N, et al. Neural interfaces by hydrogels. Extreme Mech Lett, 2019, 30: 100510 CrossRef Google Scholar

[17] Shepherd R F, Ilievski F, Choi W, et al. Multigait soft robot. Proc Natl Acad Sci USA, 2011, 108: 20400-20403 CrossRef PubMed Google Scholar

[18] Li T, Li G, Liang Y, et al. Fast-moving soft electronic fish. Sci Adv, 2017, 3: e1602045 CrossRef PubMed Google Scholar

[19] Whitesides G M. The origins and the future of microfluidics. Nature, 2006, 442: 368-373 CrossRef PubMed Google Scholar

[20] Yang C H, Chen B, Lu J J, et al. Ionic cable. Extreme Mech Lett, 2015, 3: 59-65 CrossRef Google Scholar

[21] Keplinger C, Sun J Y, Foo C C, et al. Stretchable, transparent, ionic conductors. Science, 2013, 341: 984-987 CrossRef PubMed Google Scholar

[22] Yuk H, Zhang T, Parada G A, et al. Skin-inspired hydrogel-elastomer hybrids with robust interfaces and functional microstructures. Nat Commun, 2016, 7: 12028 CrossRef PubMed Google Scholar

[23] Yu Y, Yuk H, Parada G A, et al. Multifunctional “hydrogel skins” on diverse polymers with arbitrary shapes. Adv Mater, 2019, 31: 1807101 CrossRef PubMed Google Scholar

[24] Wang X, Jiang M, Zhou Z, et al. 3D printing of polymer matrix composites: A review and prospective. Compos Part B-Eng, 2017, 110: 442-458 CrossRef Google Scholar

[25] Sun J Y, Keplinger C, Whitesides G M, et al. Ionic skin. Adv Mater, 2014, 26: 7608-7614 CrossRef PubMed Google Scholar

[26] Yang C, Suo Z. Hydrogel ionotronics. Nat Rev Mater, 2018, 3: 125-142 CrossRef Google Scholar

[27] Ekblad T, Bergström G, Ederth T, et al. Poly(ethylene glycol)-containing hydrogel surfaces for antifouling applications in marine and freshwater environments. Biomacromolecules, 2008, 9: 2775-2783 CrossRef PubMed Google Scholar

[28] Liu M, Wang S, Wei Z, et al. Bioinspired design of a superoleophobic and low adhesive water/solid interface. Adv Mater, 2009, 21: 665-669 CrossRef Google Scholar

[29] Lin L, Yi H, Guo X, et al. Nonswellable hydrogels with robust micro/nano-structures and durable superoleophobic surfaces under seawater. Sci China Chem, 2018, 61: 64-70 CrossRef Google Scholar

[30] Takahashi R, Shimano K, Okazaki H, et al. Tough particle-based double network hydrogels for functional solid surface coatings. Adv Mater Interfaces, 2018, 5: 1801018 CrossRef Google Scholar

[31] Murosaki T, Ahmed N, Gong J P. Antifouling properties of hydrogels. Sci Tech Adv Mater, 2012, 12: 064706 CrossRef PubMed Google Scholar

[32] Zander Z K, Becker M L. Antimicrobial and antifouling strategies for polymeric medical devices. ACS Macro Lett, 2017, 7: 16-25 CrossRef Google Scholar

[33] Gokaltun A, Yarmush M L, Asatekin A, et al. Recent advances in nonbiofouling PDMS surface modification strategies applicable to microfluidic technology. Technology, 2017, 05: 1-12 CrossRef PubMed Google Scholar

[34] Makamba H, Hsieh Y Y, Sung W C, et al. Stable permanently hydrophilic protein-resistant thin-film coatings on poly(dimethylsiloxane) substrates by electrostatic self-assembly and chemical cross-linking. Anal Chem, 2005, 77: 3971-3978 CrossRef PubMed Google Scholar

[35] Siow K S, Kumar S, Griesser H J. Low-pressure plasma methods for generating non-reactive hydrophilic and hydrogel-like bio-interface coatings—A review. Plasma Process Polym, 2015, 12: 8-24 CrossRef Google Scholar

[36] Berdichevsky Y, Khandurina J, Guttman A, et al. UV/ozone modification of poly(dimethylsiloxane) microfluidic channels. Sens Actuat B-Chem, 2004, 97: 402-408 CrossRef Google Scholar

[37] Hu S, Ren X, Bachman M, et al. Surface-directed, graft polymerization within microfluidic channels. Anal Chem, 2004, 76: 1865-1870 CrossRef PubMed Google Scholar

[38] Yao X, Liu J, Yang C, et al. Hydrogel paint. Adv Mater, 2019, 31: 1903062 CrossRef PubMed Google Scholar

[39] Liu Q, Nian G, Yang C, et al. Bonding dissimilar polymer networks in various manufacturing processes. Nat Commun, 2018, 9: 846 CrossRef PubMed Google Scholar

[40] Le Floch P, Yao X, Liu Q, et al. Wearable and washable conductors for active textiles. ACS Appl Mater Interfaces, 2017, 9: 25542-25552 CrossRef Google Scholar

[41] Wang Z, Xiang C, Yao X, et al. Stretchable materials of high toughness and low hysteresis. Proc Natl Acad Sci USA, 2019, 116: 5967-5972 CrossRef PubMed Google Scholar

[42] Çetinkaya O, Demirci G, Mergo P. Effect of the different chain transfer agents on molecular weight and optical properties of poly(methyl methacrylate). Optical Mater, 2017, 70: 25-30 CrossRef Google Scholar

[43] Tian K, Bae J, Bakarich S E, et al. 3D printing of transparent and conductive heterogeneous hydrogel-elastomer systems. Adv Mater, 2017, 29: 1604827 CrossRef PubMed Google Scholar

[44] Tan S H, Nguyen N T, Chua Y C, et al. Oxygen plasma treatment for reducing hydrophobicity of a sealed polydimethylsiloxane microchannel. Biomicrofluidics, 2010, 4: 032204 CrossRef PubMed Google Scholar

[45] Yang J, Bai R, Suo Z. Topological adhesion of wet materials. Adv Mater, 2018, 30: 1800671 CrossRef PubMed Google Scholar

[46] Yang J, Bai R, Li J, et al. Design molecular topology for wet-dry adhesion. ACS Appl Mater Interfaces, 2019, 11: 24802-24811 CrossRef Google Scholar

[47] Chen B, Yang J, Bai R, et al. Molecular staples for tough and stretchable adhesion in integrated soft materials. Adv Healthcare Mater, 2019, 8: 1900810 CrossRef PubMed Google Scholar

[48] Steck J, Yang J, Suo Z. Covalent topological adhesion. ACS Macro Lett, 2019, 8: 754-758 CrossRef Google Scholar

[49] Yang H, Li C, Tang J, et al. Strong and degradable adhesion of hydrogels. ACS Appl Bio Mater, 2019, 2: 1781-1786 CrossRef Google Scholar

[50] Gao Y, Wu K, Suo Z. Photodetachable adhesion. Adv Mater, 2018, 333: 1806948 CrossRef PubMed Google Scholar

[51] Merlitz H, He G L, Wu C X, et al. Surface instabilities of monodisperse and densely grafted polymer brushes. Macromolecules, 2008, 41: 5070-5072 CrossRef Google Scholar

[52] Tyng L Y, Ramli M R, Othman M B H, et al. Effect of crosslink density on the refractive index of a polysiloxane network based on 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane. Polym Int, 2013, 62: 382-389 CrossRef Google Scholar

[53] Kalcioglu Z I, Mahmoodian R, Hu Y, et al. From macro- to microscale poroelastic characterization of polymeric hydrogels via indentation. Soft Matter, 2012, 8: 3393-3398 CrossRef Google Scholar

[54] Gong J P, Kagata G, Osada Y. Friction of gels. 4. Friction on charged gels. J Phys Chem B, 1999, 103: 6007-6014 CrossRef Google Scholar

[55] Tada T, Kaneko D, Gong J P, et al. Surface friction of poly(dimethyl siloxane) gel and its transition phenomenon. Tribol Lett, 2004, 17: 505-511 CrossRef Google Scholar

[56] Yashima S, Takase N, Kurokawa T, et al. Friction of hydrogels with controlled surface roughness on solid flat substrates. Soft Matter, 2014, 10: 3192-3199 CrossRef PubMed Google Scholar

[57] Vogl O, Tirrell D. Functional polymers with biologically active groups. J Macromol Sci Chem, 1979, 13: 415–439. Google Scholar

[58] Fréchet J M. Functional polymers and dendrimers: Reactivity, molecular architecture, and interfacial energy. Science, 1994, 263: 1710-1715 CrossRef PubMed Google Scholar

  • Figure 1

    (Color online) Topoprime. (a) A substrate has a preformed entropic polymer network, but has no functional groups for chemical coupling; (b) during topoprime, the surface of the substrate is applied with a topoprimer precursor, which contains topoprimer polymers, crosslinkers, and coupling agents; (c) during cure, the crosslinkers link polymers into a topoprimer network, in topological entanglement with the substrate network. Meanwhile the coupling agents covalently incorporate active functional groups into the topoprimer network.

  • Figure 2

    (Color online) Topoprime a hydrophobic elastomer for a hydrophilic coating. (a) A cutout schematic of a substrate, topoprimer, undercoat, and topcoat. (b) The four layers connect through a stitch-bond-bond topology. The three loops represent the elastomer network, the topoprimer network, and the topcoat network, the curve represents undercoat polymers, and the two dots represent covalent bonds. (c) The chemistry of the PDMS topoprimer, PAAm undercoat, and PAAm topcoat.

  • Figure 3

    (Color online) A two-coat PDMS maintains hydrophilicity under stretch. (a) Deionized water is dripped on a sample with or without stretch. (b) Images showing the contact angles of deionized water on bare PDMS, one-coat PDMS, and two-coat PDMS, unstretched or at stretch of 2. Scale bars represent 200 µm. (c) Contact angle as a function of stretch for deionized water on various substrates. (d) A leaf-shaped sample, with the left hand side being the bare PDMS, and the right hand side being the two-coat PDMS. When water is sprayed, water beads up on the left hand side while wets homogeneously on the right hand side. Scale bars represent 1 cm.

  • Figure 4

    (Color online) Topoprime enables a hydrophobic elastomer with a hydrophilic coating resists delamination upon swell and scratch. (a) Cross-sectional view of a two-coat PDMS. At dried state, the coating is too thin to be observed (top image). At fully swollen state, the coating can be observed (bottom image). In both images, the undercoat is too thin and cannot be seen. Scale bars represent 100 μm. (b) The thickness of the topcoat swells as a function of time. (c) A hydrogel coated on a PDMS substrate with topoprimer can sustain the mechanical scratch of tweezers. (d) A hydrogel cast on a PDMS substrate without topoprimer is easily peeled off. Scale bars in (c) and (d) represent 1 mm.

  • Figure 5

    (Color online) Two-coat PDMS maintains lubricity and hydrophilicity after long-time slide. (a) Schematic of the experimental setup to test lubricity under water. The bottom surface of the sample is bonded on the loading stage. The load cell (stainless steel) contacts the top surface of the sample and rotates at an angular velocity of 1 rad s–1, and the torque is measured. (b) Friction coefficient as a function of cycle number. The two-coat PDMS exhibits a stable friction coefficient of ~0.03, lower than that of the bare PDMS and the one-coat PDMS by one order of magnitude. (c) Images showing the contact angles of deionized water on various substrates before and after 6000 cycles of slide. Scale bars represent 200 µm.