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Abstract The study reports novel photonic properties of Ti₃C₂T_xMXene flakes horizontally self‐assembled within cellulose nanofiber (CNF) matrix exhibiting unique bright multispectral colors combined with overall high transparency in the transmission regime. The intense reflection colors are reflected by individual flakes acting as effective micromirrors with shifts based on their subsurface positioning within the dielectric layers. Unique color appearances are controlled by an interplay of multiple bandgaps formed by constructive and destructive interferences at flake‐matrix interfaces. These colors manifest at the microscale under bright field optical microscopy, while the total physical film retains high transparency up to 85% and a typical greenish hue characteristic of the MXene content below 1% volume fraction. The diverse spectral appearance of 4 µm ultra‐thin films is ultimately controlled by the positioning of the horizontal flakes within the nanofiber matrix at diverse distances from the top surface. This work expands the understanding of thin films with assembled 2D materials within polymer matrix and their fundamental interactions creating new structural coloration functionalities with the potential for multispectral photonic applications such as camouflaging, photothermal treatment, and optical communication for flexible thin bio‐derived films. 

Abstract MXenes are a class of 2D materials that have gained significant attention for their potential applications in energy storage, electromagnetic interference shielding, biomedicine, and (opto)electronics. Despite their broad range of applications, a detailed understanding of the internal architecture of MXene‐based materials remains limited due to the lack of effective 3D imaging techniques. This work demonstrates the application of X‐ray micro‐computed tomography (micro‐CT) to investigate various MXene systems, including nanocomposites, coated textiles, and aerogels. Micro‐CT enables high‐resolution, 3D visualization of the internal microstructure, MXene distribution, infiltration patterns, and defect formations, which significantly influence the material's performance. Moreover, the typical technical challenges and limitations encountered during sample preparation, scanning, and post‐processing of micro‐CT data are discussed. The information obtained from optical and electron microscopy is also compared with micro‐CT, highlighting the unique advantages of micro‐CT in providing comprehensive 3D imaging and quantitative data. This study highlights micro‐CT as a powerful and nondestructive imaging tool for characterizing MXene‐based materials, providing insights into material optimization and guidelines for developing future advanced applications. 

Abstract Polyvinylidene fluoride (PVDF) is a semicrystalline polymer used in thin‐film dielectric capacitors because of its inherently high dielectric constant and low loss tangent. Its dielectric constant can be increased by the formation and alignment of its β‐phase crystalline structure, which can be facilitated by 2D nanofillers. 2D carbides and nitrides, MXenes, are promising candidates due to their notable dielectric permittivity and ability to increase interfacial polarization. Still, their mixing is challenging due to weak interfacial interactions and poor dispersibility of MXenes in PVDF. This work explores a novel method for delaminating Ti₃C₂T_xMXene directly into organic solvents while maintaining flake size and quality, as well as the use of a non‐solvent‐induced phase separation method for producing both dense and porous PVDF‐MXene composite films. A deeper understanding of dielectric behavior in these composites is reached by examining MXenes with both mixed and pure chlorine terminations in PVDF matrices. Thin‐film capacitors fabricated from these composites display ultrahigh discharge energy density, exceeding 45 J cm⁻³with 95% efficiency. The PVDF‐MXene composites are also processed using a green and sustainable solvent, propylene carbonate. 

Abstract Pentameric ligand-gated ion channels (pLGICs) mediate synaptic transmission and are sensitive to their lipid environment. The mechanism of phospholipid modulation of any pLGIC is not well understood. We demonstrate that the model pLGIC, ELIC (Erwinialigand-gated ion channel), is positively modulated by the anionic phospholipid, phosphatidylglycerol, from the outer leaflet of the membrane. To explore the mechanism of phosphatidylglycerol modulation, we determine a structure of ELIC in an open-channel conformation. The structure shows a bound phospholipid in an outer leaflet site, and structural changes in the phospholipid binding site unique to the open-channel. In combination with streamlined alchemical free energy perturbation calculations and functional measurements in asymmetric liposomes, the data support a mechanism by which an anionic phospholipid stabilizes the activated, open-channel state of a pLGIC by specific, state-dependent binding to this site. 

Abstract The origin of MXene's excellent electromagnetic shielding performance is not fully understood. MXene films, despite being inhomogeneous at the nanometer scale, are often treated as if they are compared to bulk conductors. It is reasonable to wonder if the treatment of MXene as a homogeneous material remains valid at very small film thickness and if it depends on the interlayer spacing. The goal of the present work is to test if the homogeneous material model is applicable to nanometer‐thin Ti₃C₂T_xMXene films and, if so, to investigate how the model parameters may depend on variations in MXene interlayer spacings. MXene films containing flakes with interlayer spacing between 1.9 and 5.5 Å have been prepared using various intercalating agents. It is shown that modeling the films as being homogeneous agrees with experimental tests in the microwave frequency range. Microwave conductivity and dielectric constant parameters are estimated for the homogeneous film model by fitting measured results. The direct current (DC) conductivity matches the estimated microwave conductivity on the order of magnitude. A highly effective dielectric constant provides a good fit for the lower conductivity MXene films. Optical absorption agrees with the homogeneous material model of thin films as well.