Skin-like mechanoresponsive self-healing ionic elastomer from supramolecular zwitterionic network

TLDR

Stretchable ionic skins aim to mimic natural skin sensations, yet achieving elastic recovery, self‑healing, and skin‑like strain‑stiffening in a single material remains challenging. The study demonstrates a proton‑conductive ionic skin by incorporating an entropy‑driven supramolecular zwitterionic network into a hydrogen‑bonded polycarboxylic acid matrix. The material employs two dynamic networks of differing strength that sequentially debond under stretch, resolving the trade‑off between elasticity, self‑healing, and strain‑stiffening. The resulting polyacrylic acid/betaine elastomer stretches to 1600 % with 24‑fold modulus increase, heals nearly 100 %, recovers 97.9 % with <14 % hysteresis, remains 99.7 % transparent, preserves moisture, is elastic at –40 °C, reprocessible in water, and adheres easily, making it a strong candidate for wearable iontronic sensors.

Abstract

Abstract Stretchable ionic skins are intriguing in mimicking the versatile sensations of natural skins. However, for their applications in advanced electronics, good elastic recovery, self-healing, and more importantly, skin-like nonlinear mechanoresponse (strain-stiffening) are essential but can be rarely met in one material. Here we demonstrate a robust proton-conductive ionic skin design via introducing an entropy-driven supramolecular zwitterionic reorganizable network to the hydrogen-bonded polycarboxylic acid network. The design allows two dynamic networks with distinct interacting strength to sequentially debond with stretch, and the conflict among elasticity, self-healing, and strain-stiffening can be thus defeated. The representative polyacrylic acid/betaine elastomer exhibits high stretchability (1600% elongation), immense strain-stiffening (24-fold modulus enhancement), ~100% self-healing, excellent elasticity (97.9 ± 1.1% recovery ratio, &lt;14% hysteresis), high transparency (99.7 ± 0.1%), moisture-preserving, anti-freezing (elastic at −40 °C), water reprocessibility, as well as easy-to-peel adhesion. The combined advantages make the present ionic elastomer very promising in wearable iontronic sensors for human-machine interfacing.