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

Wei Zhang,Shengtong Sun,Baohu Wu,Peiyi Wu

doi:10.1038/s41467-021-24382-4

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, <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.

Highlights

Stretchable ionic skins are intriguing in mimicking the versatile sensations of natural skins
It is noted that the addition of a specified amount of water has two main roles: (1) the resulting water content in the as-prepared ionic elastomers is almost equal to the equilibrium moisture content at a relative humidity (RH) of 60%, which avoids drastic dehydration or hydration in air
It is noted that after the first cycle, the tensile curves became narrower and almost unchanged until a steady state was reached in the following cycles, suggesting again the good elastic recovery of polyacrylic acid (PAA)/ betaine elastomer even released from very large strains

Summary

Introduction

Stretchable ionic skins are intriguing in mimicking the versatile sensations of natural skins. We report the design and preparation of a series of highly elastic, transparent, self-healable, and strain-stiffening proton-conductive ionic skins by introducing an entropy-driven supramolecular zwitterionic competing network to the hydrogenbonded (H-bonded) polycarboxylic acid chain network.

Results

Conclusion