Tough and stretchable ionogels by in situ phase separation

ABSTRACT Ionogels are compelling materials for technological devices due to their excellent ionic conductivity, thermal and electrochemical stability, and non-volatility. However, most

existing ionogels suffer from low strength and toughness. Here, we report a simple one-step method to achieve ultra-tough and stretchable ionogels by randomly copolymerizing two common

monomers with distinct solubility of the corresponding polymers in an ionic liquid. Copolymerization of acrylamide and acrylic acid in 1-ethyl-3-methylimidazolium ethyl sulfate results in a

macroscopically homogeneous covalent network with in situ phase separation: a polymer-rich phase with hydrogen bonds that dissipate energy and toughen the ionogel; and an elastic

solvent-rich phase that enables for large strain. These ionogels have high fracture strength (12.6 MPa), fracture energy (~24 kJ m−2) and Young’s modulus (46.5 MPa), while being highly

stretchable (~600% strain) and having self-healing and shape-memory properties. This concept can be applied to other monomers and ionic liquids, offering a promising way to tune ionogel

microstructure and properties in situ during one-step polymerization. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution

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FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS EMERGING APPLICATIONS OF TOUGH IONOGELS Article Open access 15 December 2023 HEALABLE SOFT MATERIALS BASED ON IONIC

LIQUIDS AND BLOCK COPOLYMER SELF-ASSEMBLY Article 01 April 2021 NANOCONFINED POLYMERIZATION LIMITS CRACK PROPAGATION IN HYSTERESIS-FREE GELS Article 26 October 2023 DATA AVAILABILITY Data

generated or analysed during this study are provided as Source Data or included in the Supplementary Information. Further data are available from the corresponding authors on request.

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Google Scholar  * Bai, R., Yang, J. & Suo, Z. Fatigue of hydrogels. _Eur. J. Mech. A_ 74, 337–370 (2019). Article  Google Scholar  Download references ACKNOWLEDGEMENTS M.D. acknowledges

support from the Coastal Studies Institute. J.H. acknowledges the support of the National Natural Science Foundation of China (11702207). We thank Prof. L. Cai for helpful discussion. We

thank Mr M. Yang and Mr X. Chen for help with 3D printing. Nano-IR analysis was performed by W.Q. at the NanoEngineering Research Core Facility (NERCF), which is partially funded by the

Nebraska Research Initiative. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * State Key Laboratory for Strength and Vibration of Mechanical Structures, International Center for Applied

Mechanics, Department of Engineering Mechanics, Xi’an Jiaotong University, Xi’an, China Meixiang Wang, Pengyao Zhang & Jian Hu * Department of Chemical and Biomolecular Engineering,

North Carolina State University, Raleigh, NC, USA Meixiang Wang, Mohammad Shamsi, Jacob L. Thelen, Vi Khanh Truong, Jinwoo Ma & Michael D. Dickey * Department of Mechanical &

Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA Wen Qian * School of Science, STEM College, RMIT University, Melbourne, Victoria, Australia Vi Khanh Truong Authors *

Meixiang Wang View author publications You can also search for this author inPubMed Google Scholar * Pengyao Zhang View author publications You can also search for this author inPubMed 

Google Scholar * Mohammad Shamsi View author publications You can also search for this author inPubMed Google Scholar * Jacob L. Thelen View author publications You can also search for this

author inPubMed Google Scholar * Wen Qian View author publications You can also search for this author inPubMed Google Scholar * Vi Khanh Truong View author publications You can also search

for this author inPubMed Google Scholar * Jinwoo Ma View author publications You can also search for this author inPubMed Google Scholar * Jian Hu View author publications You can also

search for this author inPubMed Google Scholar * Michael D. Dickey View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS M.W., J.H. and M.D.D.

conceived the idea. J.H. and M.D.D. supervised the project. M.W. carried out most of the experiments. P.Z. participated in the fracture energy measurements. M.S. and V.K.T. participated in

the SEM measurements. M.S. participated in the SAXS measurements. J.L.T. contributed to the SAXS data processing and analysis. W.Q. conducted the nano-IR measurements. J.M. contributed to

the demonstration of the falling metal ball. M.W., J.H., and M.D.D. wrote the paper, and all authors reviewed the manuscript. CORRESPONDING AUTHORS Correspondence to Jian Hu or Michael D.

Dickey. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. PEER REVIEW PEER REVIEW INFORMATION _Nature Materials_ thanks Xuanhe Zhao and the other,

anonymous, reviewer(s) for their contribution to the peer review of this work. ADDITIONAL INFORMATION PUBLISHER’S NOTE Springer Nature remains neutral with regard to jurisdictional claims in

published maps and institutional affiliations. SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION Supplementary Figs. 1–17, Notes 1–4, Tables 1 and 2, Videos 1–5 and refs. 1–7.

SUPPLEMENTARY VIDEO 1 This movie shows that the P(AAm0.8125-co-AA0.1875) ionogel is strong enough to lift a 1 kg weight, while the pure PAA and PAAm ionogel and P(AAm0.8125-co-AA0.1875)

hydrogel break. _C_m = 6 M, _C_MBAA = 0.1 mol%. SUPPLEMENTARY VIDEO 2 This movie demonstrates the ultra-tough properties of the gel when a metal ball drops on a membrane of

P(AAm0.8125-co-AA0.1875) ionogel stretched across a rigid frame. The membrane (thickness = 0.5 mm) was glued to two polyacrylate clamps with a circular opening (diameter = 7 cm). A stainless

steel ball with a diameter of 2.54 cm and mass of 64 g was dropped from a height of 2 m. Upon hitting the membrane, the ball bounced back and the membrane remained intact with small

deformation, while the P(AAm0.8125-co-AA0.1875) hydrogel was stretched to rupture after large deformation. _C_m = 6 M, _C_MBAA = 0.1 mol%. SUPPLEMENTARY VIDEO 3 This movie shows the

excellent self-healing property of the P(AAm0.8125-co-AA0.1875) ionogel. The dog-bone samples were cut into half pieces and then the pieces from two different samples were put together to

heal. After storing the sample at 80 °C for 1 h, the self-healed sample could lift the 1 kg weight. The copolymer ionogel samples were stained with methylene blue and rhodamine B. _C_m = 6 

M, _C_MBAA = 0.1 mol%. SUPPLEMENTARY VIDEO 4 This movie shows the excellent shape-memory properties of P(AAm0.8125-co-AA0.1875) ionogel by demonstrating the fast programming and recovery

process. The ionogel sample was stained with rhodamine B for visualization. _C_m = 6 M, _C_MBAA = 0.1 mol%. SUPPLEMENTARY VIDEO 5 This movie exhibits superb shape-memory behaviour of

P(AAm0.8125-co-AA0.1875) ionogel using a more complicated six-layer structure of a ‘blooming flower’. Six layers of the copolymer ionogel samples were glued together to mimic the flower bud

blooming process and the ionogels could fully recover within 25 s. The ionogel samples were stained with methylene blue. _C_m = 6 M, _C_MBAA = 0.1 mol%. SOURCE DATA SOURCE DATA FIG. 3 Source

data. SOURCE DATA FIG. 4 Source data. RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Wang, M., Zhang, P., Shamsi, M. _et al._ Tough and stretchable

ionogels by in situ phase separation. _Nat. Mater._ 21, 359–365 (2022). https://doi.org/10.1038/s41563-022-01195-4 Download citation * Received: 12 January 2021 * Accepted: 03 January 2022 *

Published: 21 February 2022 * Issue Date: March 2022 * DOI: https://doi.org/10.1038/s41563-022-01195-4 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this

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