ABSTRACT
Although electrically conductive and hydrophilic MXene sheets are promising for multifunctional fibers and electronic textiles, it is still a challenge to simultaneously enhance both conductivity and mechanical properties of MXene fibers because of the high rigidity of MXene sheets and insufficient inter-sheet interactions. Herein, we demonstrate a core-shell wet-spinning methodology for fabricating highly conductive, super-tough, ultra-strong, and environmentally stable Ti3C2Tx MXene-based core-shell fibers with conductive MXene cores and tough aramid nanofiber (ANF) shells. The highly orientated and low-defect structure endows the ANF@MXene core-shell fiber with super-toughness of ~ 48.1 MJ m-3, high strength of ~ 502.9 MPa, and high conductivity of ~ 3.0 × 105 S m-1. The super-tough and conductive ANF@MXene fibers can be woven into textiles, exhibiting an excellent electromagnetic interference (EMI) shielding efficiency of 83.4 dB at a small thickness of 213 µm. Importantly, the protection of the ANF shells provides the fibers with satisfactory cyclic stability under dynamic stretching and bending, and excellent resistance to acid, alkali, seawater, cryogenic and high temperatures, and fire. The oxidation resistance of the fibers is demonstrated by their well-maintained EMI shielding performances. The multifunctional core-shell fibers would be highly promising in the fields of EMI shielding textiles, wearable electronics and aerospace.
ABSTRACT
Although two-dimensional transition-metal carbides (MXenes) and intrinsic conductive polymers have been combined to produce functional electromagnetic interference (EMI) shielding composites, acid/alkali-responsive EMI shielding textiles have not been reported. Herein, electrically conductive polyaniline (PANI)/MXene/cotton fabrics (PMCFs) are fabricated by an efficient vacuum filtration-assisted spray-coating method for acid/alkali-responsive and tunable EMI shielding applications on the basis of the high electrical conductivity of MXene sheets and the acid/alkali doping/de-doping feature of PANI nanowires. The as-prepared PMCF exhibits a sensitive ammonia response of 19.6% at an ammonia concentration of 200 ppm. The high EMI shielding efficiency of â¼54 dB is achieved by optimizing the decorated structure of the PANI/MXene coating on the cotton fabrics. More importantly, the PMCF can act adaptively as a "switch" for EMI shielding between the efficient strong shielding of 24 dB and the inefficient weak shielding of 15 dB driven by the stimulation of hydrogen chloride and ammonia vapors. This multifunctional fabric would possess promising applications for intelligent garments, flexible electronic sensors, and smart electromagnetic wave response in special environments.
ABSTRACT
Although Ti3C2Tx MXene sheets are highly conductive, it is still a challenge to design highly stretchable MXene electrodes for flexible electronic devices. Inspired by the high stretchability of kirigami patterns, we demonstrate a bottom-up methodology to design highly stretchable and conductive polydimethylsiloxane (PDMS)/Ti3C2Tx MXene films for electromagnetic interference (EMI) shielding and pressure sensing applications by constructing wrinkled MXene patterns on a flexible PDMS substrate to create a hierarchical surface with primary and secondary surface wrinkles. The self-controlled microcracks created in the valley domains of the hierarchical film via a nonuniform deformation during prestretching/releasing cycles endow the hierarchical PDMS/MXene film with a high stretchability (100%), strain-invariant conductivity in a strain range of 0%-100%, and stable conductivities over an 1000-cycle fatigue measurement. The stretchable film exhibits a highly stable EMI shielding performance of ≈30 dB at a tensile strain of 50%, and its EMI shielding efficiency increases further to 103 dB by constructing a two-film structure. Furthermore, a highly stretchable and sensitive iontronic sensor array with integrated MXene-based electrodes and circuits is fabricated by a stencil printing process, exhibiting high sensitivity (66.3 nF kPa-1), excellent dynamic cycle stability over 1000 cycles under different frequencies, and sensitive pressure monitoring capability under a tensile strain of 50%.
ABSTRACT
Although flexible, transparent, and conductive materials are increasingly required for electromagnetic interference (EMI) shielding applications in foldable and wearable electronics, it remains a great challenge to achieve outstanding shielding performances while retaining high light transmittances. Herein, a multiscale structure optimization strategy is proposed to fabricate a transparent and conductive silver nanowire (AgNW) film with both high EMI shielding performance and high light transmittance by a scalable spray-coating technique. By decorating with a Ti3C2Tx MXene coating, the connection and integrity of the AgNW network are greatly improved by welding the nanowire junctions. Compared to a neat AgNW film (21 dB) with the same AgNW density, the Ti3C2Tx MXene-welded AgNW film shows a much higher EMI shielding performance (34 dB) with better mechanical and environmental stabilities. Furthermore, the layered structure design on the macroscopic scale results in an even higher EMI shielding efficiency of 49.2 dB with a high light transmittance of â¼83%. With the Ti3C2Tx MXene coating and the PET substrate as a triboelectric pair, the layered structure offers great flexibility for the transparent film to integrate smart sound monitoring capability. Therefore, the combination of excellent EMI shielding performance, high light transmittance, and sensitive pressure response makes the Ti3C2Tx MXene-welded AgNW films promising for many potential applications in next-generation electronics.
