Preparation And Applications Of Multifunctional Stretchable Conductors

Stretchable conductors have advantages over traditional rigid conductive materials due to their tolerance under complex or large strain deformation and stable conductivity.These conductors have great potential application in next-generation flexible electronics such as flexible electronic circuits,storage devices,implantable bioelectronics,and wearable electronic devices,etc.However,it is difficult to maintain stable electrical conductivity in complex and long-term mechanical deformation applications due to the trade-off between complex mechanical deformation and high electrical conductivity of materials.Additionally,it is crucial but challenging to improve the reliability and durability of the devices by integrating multifunctional components such as self-healing and temperature tolerance properties into one device,for whose mechanical and electrical properties could be repaired in time under extreme temperature conditions or even when they are damaged.Here in,conductive silver nanowires（Ag NWs）and other functional elements were used to fabricated hierarchically ordered micro-nanostructures by the ice template method,and the interfacial interactions between the hierarchical conductive network and the polymer network were enhanced by using metal-sulfur（Ag-SR）coordination to prepared flexible stretchable materials with multifunctional performances such as super-stretchability,high conductivity,temperature tolerance,and self-healing performances,etc.Their applications in the field of flexible devices were explored,which has important application potential in the field of next generation intelligent wearable and energy storage devices.The main research results are as follows:（1）The conductive Ag NWs and Ag nanoparticle-modified carbon nanotubes（Ag-CNTs）were assembled into Ag NWs/Ag-CNTs aerogels with multiple conductive pathways by ice template method,and the highly conductive Ag NWs/Ag-CNTs aerogels was obtained by roasting the aerogel.A multifunctional organhydrogel with up to 2100%super-stretchability,～965 S cm^-1 high conductivity,and excellent self-healing properties at low temperature（-35 ^oC）was prepared by backfilling and in-situ polymerization of sulfur-containing polyacrylamide organohydrogel into highly conductive aerogel based on dynamic Ag-SR coordination bonds.Notably,the organohydrogel demonstrared rapid NIR-light and electric-responsive self-healing ability due to the dynamic reversible properties of multiple hydrogen bonds and Ag-SR coordination bonds and the synergistic effect of multiple conductive networks in the gel.And this organohydrogel could be designed as wearable sensors to detect various simple motions of human body,which exhibited good sensing performance.（2）An autonomous self-healing and intrinsically stretchable supercapacitor that can work at all-climate environments was for the first time assembled by universally self-healing and highly stretchable organohydrogel electrodes with record-high temperature-invariant conductivity of～965 S cm^-1.Benefiting from multiple hydrogen bonding and dynamic metal coordination combined with electrochemistry-favorable components and integrated device configuration,the resultant supercapacitor exhibited outstanding long-term stability with 97.1%of capacitance retention over 10,000 cycles,high stretchability of 1080%,instantaneous and complete self-healing of capacitive performance,real-time mechanical healing with 91%of recovery efficiency,and 85.2%of original capacitance retained after 20 cut-healing cycles at-35 ^oC.Notably,90.5%of mechanical recovery was rapidly achieved by 30 cyclic voltammetry（CV）cycles with100%capacitance delivered at 80 ^oC.The superiorities in stretchability,self-healability and all-climate tolerance enabled the supercapacitor presented here as the best performer among the flexible supercapacitors reported to date.（3）Highly aligned and anisotropic magnetic Fe₃O₄-Ag NWs aerogels were prepared by magnetic field-assisted bidirectional freezing method.Then,magnetic organohydrogels with anisotropic properties were prepared based on dynamic Ag-SR bonding between the polymer chains and the conductive network of Fe₃O₄-Ag NWs to form chemical cross-linking.The magnetic organohydrogel maintained a mechanical anisotropy difference of 2-fold and conductive anisotropy of up to 300-fold,originating from the microstructure of highly aligned Fe₃O₄-Ag NWs nanowires.Meanwhile,the magnetic organohydrogel had a self-healing efficiency of up to 97.8%after NIR 60 s stimulation due to the dynamic reversibility of a large number of hydrogen bonds and Ag-SR coordination bonds.In addition,the magnetic organohydrogel was assembled into a cross-stacked multidimensional sensor and applied to detect the motion of human multi-degrees-of-freedom synovial joints,presenting new potential for more advanced applications of flexible strain sensors.