| Intrinsic stretchable ionic conductors represented by hydrogels and ionogels have received tremendous attention in flexible electronics like soft robotics,electronic skin,and energy storage devices in recent years.The promising application of soft electronics in aerospace and national defense areas gives rise to increasing requirements to soft conductors adaptable to extreme environments.However,hydrogels suffer from freezing at sub-zero temperatures and dehydration in the ambient environment,which severely hinder their practical application.Although ionogels possess better low-temperature and high-temperature tolerance,they are still restricted by the leakage of ionic liquids.Therefore,it is still challenging to develop soft ionic conductors with low-temperature tolerance and high stability.Polymeric ionic liquids(PILs)are a type of novel polyelectrolyte with outstanding stability as well as high tunability of structure and glass transition temperature,making them desirable candidate for novel ionic conductors.Since pure PILs exhibit poor mechanical properties,they are often reinforced by inorganic materials.Nevertheless,traditional PIL/inorganic composites share problems of unfavorable transparency and mechanical performance owing to weak interactions between the nanofillers and PIL matrices.In this work,we presents a general strategy combining anion exchange and in-situ polymerization process to introduce layered double hydroxides(LDHs)into PILs to fabricate anti-freezing(-81℃),transparent(88%),ionic conductive(3.3 mS cm-1),and stretchable(600%)PIL/LDH nanocomposite elastomer.The morphology and structure characterization of PIL/LDH composites proved complete exfoliation and uniform distribution of LDHs in the PIL matrix as well as electrostatic interactions between LDH nanosheets and PILs.Further mechanical tests demonstrated the strength and fracture toughness of the PIL/LDH composite have increased by 6 times.Notably,mechanical and electrical tests at subzero temperatures showed that the PIL/LDH composite exhibited tensile strain of more than 300%,favorable ionic conductivity and elastic resilience even at-65℃.Furthermore,PIL/LDH based strain sensor and pressure sensor presented stable and sensitive response.Soft sensors assembled with PIL/LDH elastomer can detect human body movements and locations of different targets at-65℃,displaying great potential in the field of wearable electronics and extreme environment detectors.This study provides a powerful platform for the development of flexible electronics for future applications in extreme and complex environments. |
