Ultrathin and flexible MXene-contained electromagnetic interference shielding composite paper designed with a protective hydrogel film

MXene-contained paper is a good choice to design ultrathin and flexible electromagnetic interference(EMI)shielding materials.However,the deficiencies in strength and stability of MXene-contained paper impede its practical applications.Herein,a composite paper was proposed to address the problems,in which a filter paper was modified with a three-layer structured surface via a facile layer-by-layer coat-ing procedure.Specifically,the TEMPO-oxidized cellulose nanofibers(TOCN)/cationic starch(CS)/MXene gel layer and TOCN/MXene nacre structure layer ensured the good EMI shielding and mechanical per-formances of the composite paper,while the uppermost TOCN/CS hydrogel film layer mainly protected MXene.The composite paper achieved an EMI SE of 40.3 dB at a thickness of merely 0.1894 mm(SE/t value of ca.212.8 dB mm-1,SSE/t values of ca.13216 dB cm2 g-1)and the total MXene dosage was 20 g m-2.Its tensile strength could be up to 11.7 MPa while the original filter paper was 6.4 MPa.Four pieces of this composite papers could be easily packed together to attain an EMI SE of nearly 70 dB.Importantly,the hydrogel film layer efficiently protected the MXene and maintained the EMI shielding performance of the composite paper when immersed in different liquids including water,HC1(1 M)and ethanol,due to the dense and compact structure of hydrogel film layer.This work provides a practical way to develop ultrathin,flexible and durable EMI shielding materials.     

Robust liquid metal reinforced cellulose nanofiber/MXene composite film with Janus structure for electromagnetic interference shielding and electro-/photothermal conversion applications

MXene-based composite films are regarded as up-and-coming multifunctional electromagnetic interfer-ence(EMI)shielding materials.However,the conflict between strong mechanical properties and high electrical conductivity hinders their application in modern integrated electronics.Herein,in virtue of density-induced sedimentation,robust and multifunctional liquid metals-reinforced cellulose nanofibers(CNF)/MXene(LMs-CNF/MXene)composite films with Janus structure are fabricated by one-step vacuum-assisted filtration method.Not only does the nacre-like structure of the CNF/MXene layer not destroy,but the deposited liquid metals(LMs)layer can serve as conductive potentiation.Due to the special Janus structure,an\"absorption-reflection-reabsorption\"shielding process is created in LMs-CNF/MXene composite film to strengthen EMI shielding performance.Its shielding effectiveness can reach 51.9 dB at～27 μm,and the reflection coefficient falls to 0.89,below those of reported MXene-based shielding films.Meanwhile,the CNF/MXene layer can endow composite films with excellent mechanical properties with a super tensile strength of 110.3 MPa.Notably,the LMs-CNF/MXene EMI shielding composite films also integrate outstanding photo-/electrothermal conversion performances,which can effectively deice out-doors.The robust LMs-CNF/MXene EMI shielding composite films with satisfying photo-/electrothermal performances have extensive application prospects,such as aerospace,wearable electronics,and portable electronics.     

Bionic-leaf vein inspired breathable anti-impact wearable electronics with health monitoring,electromagnetic interference shielding and thermal management

Breathable and stretchable conductive materials are ideal for healthcare wearable electronic devices.However,the tradeoff between the sensitivity and detection range of electronic sensors and the chal-lenge posed by simple-functional electronics limits their development.Here,inspired by the bionic-leaf vein conductive path,silver nanowires(AgNWs)-Ti3C2Tx(MXene)hybrid structure assembled on the non-woven fabrics(NWF)is well sandwiched between porous polyborosiloxane elastomer(PBSE)to construct the multifunctional breathable wearable electronics with both high anti-impact performance and good sensing behavior.Benefiting from the high conductive AgNWs-MXene hybrid structure,the NWF/AgNWs-MXene/PBSE nanocomposite exhibits high sensitivity(GF=1158.1),wide monitoring range(57％),con-trollable thermal management properties,and excellent electromagnetic interference shielding effect(SET=41.46 dB).Moreover,owing to the wonderful shear stiffening effect of PBSE,the NWF/AgNWs-MXene/PBSE possesses a high energy absorption performance.Combining with deep learning,this breath-able electronic device can be further applied to wireless sensing gloves and multifunctional medical belts,which will drive the development of electronic skin,human-machine interaction,and personalized healthcare monitoring applications.     

PEDOT:PSS-patched magnetic graphene films with tunable dielectric genes for electromagnetic interference shielding and infrared stealth

The intelligent era brings electronics closer to humans,but also produces a large scale of electromag-netic(EM)radiation simultaneously,which causes serious harm to health and high sophisticated equip-ment.Exploring the underlying response logic of EM materials is urgently needed to face the challenge of EM interference(EMI)and secondary EM pollution better.Herein,PEDOT:PSS-patched magnetic graphene films are fabricated by vacuum-assisted molecular patching engineering,with tunable EM wave response.Based on the observation of micro-nano structure,the dielectric genes are visually revealed,which offers a bran-new horizon for the optimization of EM properties.Impressively,the constructed films achieve double band shielding toward gigahertz wave and infrared radiation.The optimal EMI shielding efficiency exceeds 99％,and covers the entire X-band.Meanwhile,the green shielding index rises from 0.3 to 0.6,indicating that it is a potential green EMI shielding materials.Furthermore,the periodic macroscopic interfaces and the inherent thermal anisotropy endow the films with thermal insulation and flexible in-frared stealth functions in simulated thermal environments.This work refreshes the insight into multi-band shielding,providing a new idea to EM energy governance.     

Aerosol based fabrication of a Cu/polymer and its application for electromagnetic interference shielding

The effect of a catalytic surface activation on the electromagnetic interference shielding of Cu deposited polymer substrates was investigated. The surface of polymer substrates was catalytically activated by different methods respectively adopted Pd aerosol nanoparticles and Sn-Pd wet chemical processes. Although both activations initiated the deposition of Cu on the substrates, differences such as morphology (Pd aerosol: ~80 nm vs Sn-Pd: ~ 140 nm, in Cu grain size) and composition (Pd aerosol: Cu and Pd vs Sn-Pd: Cu, Pd, Sn, and Cl) of Cu deposits were presented. Specimens activated using Pd aerosol nanoparticles showed a higher range of shielding effectiveness by about 4-10 dB than those activated by Sn-Pd processes in 2-18 Ghz frequencies.     

Skin-inspired self-healing polycaprolactone-based composite induced by photo/electro stimuli for highly absorbed and stable electromagnetic interference shielding

The endeavor to attain prolonged stability and heightened electromagnetic interference shielding effec-tiveness(EMI SE)in polymer-matrix composites remains an arduous pursuit,particularly when subjected to external mechanical trauma or adverse environmental conditions.In this context,a self-healing and efficient EMI shielding polycaprolactone(PCL)composite with a unique electromagnetic gradient and interface-metalized segregated structure is assembled through layer-by-layer casting and a hot-pressing process.The combined effect of the induction of the electromagnetic gradient layer and the massive mul-tiple interface reflection and scattering from the segregated-like structure results in an exceptional EMI SE of 57.0 dB and a low reflection(R)value of only 0.28.Additionally,the composite boasts impressive photothermal and electrothermal properties,allowing for self-healing under solar irradiation or electri-cal stimulation.Remarkably,this self-healing capability has been demonstrated through five cutting and healing cycles,exhibiting an impressive EMI SE retention rate of 88％.Consequently,the composite with rapid photo/electro-driven self-healing properties will be able to maintain EMI shielding performance.