High-strength, flexible, and multifunctional characteristics are highly desirable for electromagnetic interference (EMI) shielding materials in the field of electric devices. In this work, inspired by natural nacre, we fabricated large-scale, layered MXene/amarid nanofiber (ANF) nanocomposite papers by blade-coating process plus sol–gel conversion step. The as-synthesized papers possess excellent mechanical performance, that is, exceptional tensile strength (198.80 ± 5.35 MPa), large strain (15.30 ± 1.01%), and good flexibility (folded into various models without fracture), which are ascribed to synergetic interactions of the interconnected three-dimensional network frame and hydrogen bonds between MXene and ANF. More importantly, the papers with extensive continuous conductive paths formed by MXene nanosheets present a high EMI shielding effectiveness of 13188.2 dB cm2 g–1 in the frequency range of 8.2–12.4 GHz. More interestingly, the papers show excellent Joule heating performance with a fast thermal response (<10 s) and a low driving voltage (≤4 V). As such, the large-scale MXene/ANF papers are considered as promising alternatives in a wide range of applications in electromagnetic shielding and thermal management.

The aggregation behavior of amphiphilic block copolymer polystyrene-b-poly(acrylic acid) (PS-b-PAA) at the air-water interface was investigated through surface pressure measurements (isotherms, compression-expansion hysteresis and compression relaxation experiments), Brewster Angle Microscopy (BAM) imaging and Atomic Force Microscopy (AFM) imaging. It is found that PS-b-PAA (M n ¼ 11 490 g mol À1 , PAA wt%$62%) forms a stable Langmuir monolayer on the water surface (pH ¼ 7) by using N,Ndimethylformamide (DMF) as the spreading solvent. The aggregation of block copolymer is induced by an initial diffusion of DMF into water from the interface. Upon compression of the film, the pseudoplateau observed in the Langmuir isotherm corresponds to a "pancake-to-brush" transition with the PAA chains gradually dissolving in the water subphase and stretching underneath the PS cores. Based on the isotherms and the BAM images, it is suggested that the polymer chain dynamics in spreading solutions with different concentrations at the time of solvent diffusion influence the interfacial behavior of block copolymers significantly. The Langmuir-Blodgett (LB) films prepared at different surface pressures from different spreading solution concentrations were scanned by AFM. A variety of morphologies such as wormlike, porous and reticulate structures, and dots were observed.The isotherms and AFM images show the spreading solution concentration and surface pressure dependence of the aggregation behavior of PS-b-PAA copolymer at the air-water interface.

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Diblock copolymers poly(methyl methacrylate)-block-polystyrene with three different molar ratios [poly(methyl methacrylate)/polystyrene (PS) 5 1:1, 1:1.5, and 1:1.8] were synthesized by atom transfer radical polymerization and used as a polymer matrix for gel polymer electrolytes (GPEs). The positron annihilation lifetime spectroscopy was applied to determine the free-volume behaviors of different GPEs, respectively. We illustrated that a proper PS ratio may led to the formation of a high fraction of free volume, and the influence of the PS ratio on the free-volume fraction was caused by the different morphologies of the GPEs because of the different packing densities of the PS rigid block. The ionic conductivity was correlated with the free volume in the GPE through the study of the ionic conductivity dependence on the temperature; this followed the Vogel-Tamman-Fulcher equation. Moreover, an ionic conductive model was proposed, in which variations of the free-volume behavior provide different ionic-conducting abilities. Thermogravimetric analysis indicated that GPEs based on different block copolymers exhibited high liquid-electrolyte preservation properties.

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