The increasing demand for wearable electronics and the intensification of electromagnetic pollution have boosted the exploration of high-performance flexible microwave absorption (MA) materials. Herein, the hierarchical Ti3C2T x MXene/Ni chain/ZnO array hybrid nanostructures are rationally constructed on cotton fabric for acquiring enhanced MA performance and durable self-cleaning ability. Based on the high dielectric loss capacity of MXenes and ZnO arrays, by controlling dip-coating numbers of Ni chains, the magnetic loss can be manipulated to modulate the impedance matching, reflection loss (RL), and effective absorption bandwidth (EAB, the bandwidth of RL < −10 dB). The minimum RL value of the designed fabric can reach −35.1 dB at 8.3 GHz with a thickness of 2.8 mm, and its EAB can cover the whole X-band with only a 2.2 mm thickness. In addition, the designed fabric also exhibits superior liquid repellency and durable self-cleaning ability due to the combination of the hybrid nanostructures and a superhydrophobic coating. This work provides an insight for rational design of textile-based MA materials, showing potential applications in flexible and wearable functional electronics.

a b s t r a c tThree-dimensional (3D) five-directional braided composites are significant structural materials in the fields of astronauts and aeronautics. On the basis of the 3D five-directional braiding process, three types of microstructural unit cell models are established with respect to the interior, surface and corner regions. The mathematical relationships among the structural parameters, such as fiber orientation, fiber volume fraction, the yarn packing factor, are derived. By using these three unit cell models, a micromechanical prediction procedure is described to simulate the stiffness and strength properties of 3D fivedirectional braided composites. Only the in situ constituent fiber and matrix properties of the composites and the fiber volume proportion are required in the simulation. The stress states generated in the constituent fiber and matrix materials are explicitly correlated with the overall applied load on the composites. The predictive stiffness and strength are in good agreement with available experimental data, which demonstrates the applicability of the present analytical model.

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The graphene nanosheets-based epoxy resin coating (0, 0.1, 0.4 and 0.7 wt %) was prepared by a situ-synthesis method. The effect of polyvinylpyrrolidone/reduced graphene oxide (PVP-rGO) on mechanical and thermal properties of epoxy resin coating was investigated using nanoindentation technique and thermogravimetric analysis, respectively. A significant enhancement (ca. 213% and 73 °C) in the Young modulus and thermal stability of epoxy resin coating was obtained at a loading of 0.7 wt %, respectively. Furthermore, the erosion resistance of graphene nanosheets-based epoxy resin coating was investigated by electrochemical measurement. The results showed also that the Rrcco (ca. 0.3 mm/year) of graphene nanosheets-based epoxy resin coating was far lower than neat epoxy resin (1.3 mm/year). Thus, this approach provides a novel route for improving erosion resistance and mechanical-thermal stability of polymers coating, which is expected to be used in mechanical-thermal-corrosion coupling environments.

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and easy corrosion. [2] By contrast, conductive polymer composites, consisting of conductive fillers inserted in a polymer matrix, have drawn increasing attention from researchers due to their lightweight, good processability, chemical stability, and structural flexibility. [3] These promising potential conductive polymer composites, particularly high-performance and ultrathin ones, are expected to be used as EMI shielding materials in soft and flexible electronic devices in the future, such as foldable phones and wearable devices. [4] MXenes, an emerging family of 2D transition metal carbides and/or nitrides, possess a formula M n+1 X n T x , where M is an early transition metal, X is carbon and/or nitrogen, n = 1, 2, or 3, and T x denotes the surface termination groups (O, OH, and F). [5] MXenes exhibit efficient electron transport and dipole polarization attributing to their surface termination groups and intrinsic defects, which are conducive to attenuating electromagnetic wave. [6] Compared to the well-studied carbon-based materials, such as carbon nanotubes and graphene, MXenes integrating metallic conductivity and versatile surface chemistry are considered as more promising EMI shielding materials for next-generation portable and wearable smart devices. [7] The discoverers of MXenes, Gogotsi and co-workers reported the freestanding Ti 3 C 2 T x MXene film (thickness 45 µm) with a superior EMI shielding effectiveness (SE) of 92 dB. [8] Liu et al. [9] subsequently prepared a lightweight MXene foam via hydrazine-induced foaming process. Compared to unfoamed MXene film (thickness 6 µm), after foaming, the favorable porous structure further improves EMI SE from 53 to 70 dB. It is noticeable that the EMI SE of MXenes exceeds many carbon-based materials. [7a,10] Nevertheless, compared with the prosperity of carbon-based conductive polymer composites, the development of MXene-based ones is still in an infant stage. Introducing MXenes into different polymer matrices is one of the simplest and most effective preparation strategies. MXene/polyacrylamide nanocomposite films have an electrical conductivity of 3.3 S m −1 with 75 wt% MXene loading. [11] The electrical conductivity of MXene/polyvinyl alcohol films is 1.3 S m −1 when MXene loading is 60 wt%. [12] The electrical conductivity and EMI SE of MXene/cellulose nanofiber composite paper (thickness 74 µm) are 115.5 S m −1 and 25.8 dB, respectively, at a high MXene loading of 80 wt%. [10] MXene/sodium Developing high-performance electromagnetic interference (EMI) shielding materials has become increasingly important along with the upcoming 5G communication era and the boom of wearable devices. However, the large thickness and poor mechanical properties of most of EMI shielding materials cannot satisfy the above critical requirements. Here, flexible and ultrathin poly(vinylidene fluoride) (PVDF)/MXene/Ni chain composite films are fabricated. Interestingly, by combining quasi-1D Ni chains and 2D MXenes, the average EMI shielding effectiveness of the PVDF/MXene...

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