Bicontinuous vitrimer heterogels with wide-span switchable stiffness-gated iontronic coordination.

Zhao, Ziguang; Cao, Ziquan; Wu, Zhixin; Du, Wenxin; Meng, Xue; Chen, Huawei; Wu, Yuchen; Jiang, Lei et al. · Sci Adv · 2024

basic_science · Level V

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Abstract

Currently, it remains challenging to balance intrinsic stiffness with programmability in most vitrimers. Simultaneously, coordinating materials with gel-like iontronic properties for intrinsic ion transmission while maintaining vitrimer programmable features remains underexplored. Here, we introduce a phase-engineering strategy to fabricate bicontinuous vitrimer heterogel (VHG) materials. Such VHGs exhibited high mechanical strength, with an elastic modulus of up to 116 MPa, a high strain performance exceeding 1000%, and a switchable stiffness ratio surpassing 5 × 10<sup>3</sup>. Moreover, highly programmable reprocessing and shape memory morphing were realized owing to the ion liquid-enhanced VHG network reconfiguration. Derived from the ion transmission pathway in the ILgel, which responded to the wide-span switchable mechanics, the VHG iontronics had a unique bidirectional stiffness-gated piezoresistivity, coordinating both positive and negative piezoresistive properties. Our findings indicate that the VHG system can act as a foundational material in various promising applications, including smart sensors, soft machines, and bioelectronics.