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Abstract When a few drops of acid (hydrochloric, acrylic, propionic, acetic, or formic) are added to a colloid comprised of 1D lepidocrocite titanate nanofilaments (1DLs)–2 × 2 TiO₆octahedra in cross‐section–a hydrogel forms, in many cases, within seconds. The 1DL synthesis process requires the reaction between titanium diboride with tetramethylammonium (TMA⁺), hydroxide. Using quantitative nuclear magnetic resonance (qNMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), the mass percent of TMA⁺after synthesis is determined to be ≈ 13.1 ± 0.1%. The TMA⁺is completely removed from the gels after 2 water soak cycles, resulting in the first completely inorganic, TiO₂‐based hydrogels. Ion exchanging the TMA⁺with hydronium results in gels with relatively strong hydrogen bonds. The hydrogels' compression strengths increased linearly with 1DL colloid concentration. At a 1DL concentration of 45 g L⁻¹, the compressive strength, at 80% deformation when acrylic acid is used, is ≈325 kPa. The strengths are ≈ 50% greater after the TMA⁺is removed. The removal of all residual organic components in the hydrogels, including TMA⁺, is confirmed by qNMR, Fourier‐transformed infrared spectroscopy (FTIR), and TGA/DSC. The 1DL phase is retained after gelation, TMA⁺removal, and 80% compression. 

Abstract An innovative process to multifunctional vitrimer nanocomposites with a percolative MXene minor phase is reported, marking a significant advancement in creating stimuli‐repairable, reinforced, sustainable, and conductive nanocomposites at diminished loadings. This achievement arises from a Voronoi‐inspired biphasic morphological design via a straight‐forward three‐step process involving ambient‐condition precipitation polymerization of micron‐sized prepolymer powders, aqueous powder‐coating with 2D MXene (Ti₃C₂T_z), and melt‐pressing of MXene‐coated powders into crosslinked films. Due to the formation of MXene‐rich boundaries between thiourethane vitrimer domains in a pervasive low‐volume fraction conductive network, a low percolation threshold (≈0.19 vol.%) and conductive polymeric nanocomposites (≈350 S m⁻¹) are achieved. The embedded MXene skeleton mechanically bolsters the vitrimer at intermediate loadings, enhancing the modulus and toughness by 300% and 50%, respectively, without mechanical detriment compared to the neat vitrimer. The vitrimer's dynamic‐covalent bonds and MXene's photo‐thermal conversion properties enable repair in minutes through short‐term thermal treatments for full macroscopic mechanical restoration or in seconds under 785 nm light for rapid localized surface repair. This versatile fabrication method to nanocoated pre‐vitrimer powders and morphologically complex nanocomposites is compatible with classic composite manufacturing, and when coupled with the material's exceptional properties, holds immense potential for revolutionizing advanced composites and inspiring next‐generation smart materials. 

The MAB phases are atomically layered, ternary or quaternary transition metal (M) borides (TMBs), with the general formula (MB)_{2 z}A_x(MB₂)_y( z = 1–2; x = 1–2; y = 0–2), whose structures are composed of a transition M-B sublattices interleaved by A-atom (A = Al,Zn) mono- or bilayers. Most of the MAB phases were discovered before the 1990s, but recent discoveries of intriguing magnetocaloric properties, mechanical deformation behaviour, catalytic properties, and high-temperature oxidation resistance has led to their ‘re-discovery’. Herein, MAB phase synthesis is reviewed and their magnetic, electronic, thermal, and mechanical properties are summarized. Because the M-B layers in the MAB phases structurally resemble their corresponding binaries of the same M:B stoichiometry, the effects of the A-layers on properties are discussed. Inconsistencies in the literature are critically assessed to gain insights on the processing-structure-property relations, suggest fruitful avenues for future research, and identify limitations for prospective applications. 

Abstract Van der Waals interactions in 2D materials have enabled the realization of nanoelectronics with high‐density vertical integration. Yet, poor energy transport through such 2D–2D and 2D–3D interfaces can limit a device's performance due to overheating. One long‐standing question in the field is how different encapsulating layers (e.g., contact metals or gate oxides) contribute to the thermal transport at the interface of 2D materials with their 3D substrates. Here, a novel self‐heating/self‐sensing electrical thermometry platform is developed based on atomically thin, metallic Ti₃C₂MXene sheets, which enables experimental investigation of the thermal transport at a Ti₃C₂/SiO₂interface, with and without an aluminum oxide (AlO_x) encapsulating layer. It is found that at room temperature, the thermal boundary conductance (TBC) increases from 10.8 to 19.5 MW m⁻²K⁻¹upon AlO_xencapsulation. Boltzmann transport modeling reveals that the TBC can be understood as a series combination of an external resistance between the MXene and the substrate, due to the coupling of low‐frequency flexural acoustic (ZA) phonons to substrate modes, and an internal resistance between ZA and in‐plane phonon modes. It is revealed that internal resistance is a bottle‐neck to heat removal and that encapsulation speeds up the heat transfer into low‐frequency ZA modes and reduces their depopulation, thus increasing the effective TBC.