Anomalous Stiffening of a Conjugated Polymer During Electrochemical Oxidation

Abstract The mechanical mismatch between semiconductors and biological tissues can be a challenge for the development of conformal bioelectronics. Organic mixed ionic‐electronic conductors (OMIECs) such as conjugated polymers with oligoether side chains are promising materials due to their low stiffness, which may minimize adverse immune reactions and thus promote biocompatibility. However, significant volume changes during electrochemical cycling—driven by ion and water ingression and expulsion—can lead to drastic changes in stiffness, complicating device‐tissue mechanical matching across redox states. Here, the electromechanical response of a thienothiophene‐based conjugated polymer with triethylene glycol side chains is investigated. Electrochemical nanoindentation and atomic force microscopy reveal a modest and reversible increase in elastic modulus at room temperature from ≈70 to more than 120 MPa upon electrochemical oxidation. This unusual mechanical stability is attributed to a reversible increase in π‐stacking that compensates for swelling‐induced softening. These findings demonstrate that it is feasible to design OMIEC materials with stable mechanical properties across redox states, opening new possibilities for compliant and tissue‐matched bioelectronic interfaces that remain mechanically invariant during operation.

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Publication Details

Journal
Advanced Functional Materials
Published
2025-10-17
DOI
https://doi.org/10.1002/adfm.202519980
Citations
1
Primary Topic
Conducting polymers and applications
Type
article
Field-Weighted Citation Impact
0.61

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article

Anomalous Stiffening of a Conjugated Polymer During Electrochemical Oxidation

Ruiheng Wu, Meghna Jha, Yadong Zhang, Christian Müller et al.
1 citations
Advanced Functional Materials
Conducting polymers and applications
0.61
article

Anomalous Stiffening of a Conjugated Polymer During Electrochemical Oxidation

Ruiheng Wu, Meghna Jha, Yadong Zhang, Christian Müller, Dilara Meli, Sri Harish Kumar Paleti, Joost Kimpel, Judit Tarrés, Seth R. Marder, Hang Yu, Jonathan Rivnay, Bryan D. Paulsen, Chiara Musumeci, Stephen Barlow, Zachary Laswick, Young-Seok Kim, Di Zhu, Jenny Nelson
article en
1 citations

Abstract

Abstract The mechanical mismatch between semiconductors and biological tissues can be a challenge for the development of conformal bioelectronics. Organic mixed ionic‐electronic conductors (OMIECs) such as conjugated polymers with oligoether side chains are promising materials due to their low stiffness, which may minimize adverse immune reactions and thus promote biocompatibility. However, significant volume changes during electrochemical cycling—driven by ion and water ingression and expulsion—can lead to drastic changes in stiffness, complicating device‐tissue mechanical matching across redox states. Here, the electromechanical response of a thienothiophene‐based conjugated polymer with triethylene glycol side chains is investigated. Electrochemical nanoindentation and atomic force microscopy reveal a modest and reversible increase in elastic modulus at room temperature from ≈70 to more than 120 MPa upon electrochemical oxidation. This unusual mechanical stability is attributed to a reversible increase in π‐stacking that compensates for swelling‐induced softening. These findings demonstrate that it is feasible to design OMIEC materials with stable mechanical properties across redox states, opening new possibilities for compliant and tissue‐matched bioelectronic interfaces that remain mechanically invariant during operation.

Advanced Functional MaterialsVol. 36(19)
Linköping University (SE), Northwestern University (US), University of Colorado Boulder (US), Imperial College London (GB), Chalmers University of Technology (SE)
National Science Foundation, U.S. Department of Energy, Northwestern University, Linköpings Universitet, Knut och Alice Wallenbergs Stiftelse, Vetenskapsrådet, China Scholarship Council, Office of Science, Engineering and Physical Sciences Research Council, Office of Naval Research, Division of Materials Research, Basic Energy Sciences, SLAC National Accelerator Laboratory
Openalex Percentile: Top 29%
Conducting polymers and applications
0.61
DOIOpen Access PDFOpenAlex
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