Skin-Inspired Healable Conductive Elastomers with Exceptional Strain-Adaptive Stiffening and Damage Tolerance

Stretchable conductive elastomers play an irreplaceable role in flexible electronic devices. However, stretchable conductive elastomers are usually soft and susceptible to damage. In this study, inspired from skin, highly stretchable and elastic conductive elastomers integrated with damage resistance, damage tolerance, and healability are fabricated by loading ionic liquids (ILs) within the polyurethane (PU) elastomers of the multiblock polymers of poly­(dimethylsiloxane) (PDMS)/polycaprolactone (PCL) coordinated with Zn2+ ions. The mechanically robust conductive elastomer, with a tensile strength of ∼15.2 MPa and a stretchability of ∼2668%, has a satisfactory ionic conductivity of 2.9 × 10–4 S cm–1. The conductive elastomer exhibits exceptional strain-adaptive stiffening, with an ∼100-fold increase in modulus when being fully stretched. The strain-adaptive stiffening endows the elastomer with excellent damage resistance. Meanwhile, the conductive elastomer has a record-high fracture energy of ∼33.8 kJ m–2. The notched conductive elastomer can prevent the propagation of the notch up to a strain of ∼2400%. The exceptional strain-adaptive stiffening and damage tolerance originate from the in situ formed phase-separated domains, which are deformable and disintegrable under an external force to significantly strengthen the elastomer and dissipate energy. Furthermore, the conductive elastomer can be conveniently healed under heating to restore its original conductivity and mechanical properties.