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Abstract Two-dimensional carbides and nitrides, known as MXenes, are promising for water-processable coatings due to their excellent electrical, thermal, and optical properties. However, depositing hydrophilic MXene nanosheets onto inert or hydrophobic polymer surfaces requires plasma treatment or chemical modification. This study demonstrates a universal salt-assisted assembly method that produces ultra-thin, uniform MXene coatings with exceptional mechanical stability and washability on various polymers, including high-performance polymers for extreme temperatures. The salt in the Ti₃C₂T_xcolloidal suspension reduces surface charges, enabling electrostatically hydrophobized MXene deposition on polymers. A library of salts was used to optimize assembly kinetics and coating morphology. A 170 nm MXene coating can reduce radiation temperature by ~200 °C on a 300 °C PEEK substrate, while the coating on Kevlar fabric provides comfort in extreme conditions, including outer space and polar regions. 

Abstract The rapid development in nanotechnology has necessitated accurate and efficient assembly strategies for nanomaterials. Monolayer assembly of nanomaterials (MAN) represents a challenging and important architecture to manufacture and is critical in understanding interactions among nanomaterials, solvents, and substrates. MAN enables highly tunable performance in electronic and photonic devices. This review summarizes the recent progress on the methods to achieve MAN and discusses important control factors. Moreover, the importance of MAN is elaborated by a broad range of applications in electronics and photonics. In the end, the opportunities as well as challenges in manufacturing and new applications are outlooked. 

Abstract Direct ink writing (DIW) using polymer‐particle composite inks is a new research area enabling a wide range of new functionalities. Despite extensive studies, there remains a need for a deeper understanding of how particle size and loading specifically influence printability, especially in the nano range. This work aims to systematically evaluate the effects of SiO₂nanoparticle size (26–847 nm) and loading on printability within a polydimethylsiloxane (PDMS) matrix. For the single‐layer printing process, which is influenced by the substrate properties, a 3D printing line analysis (3D‐PLA) is developed to monitor the top and side views of printed lines. It is found that line width varies with ink composition and substrate, while the line height decreases with solvent evaporation, indicating a strong confinement effect from the substrate. For multilayer structures, dual‐layer printing analysis (DLPA) is utilized to evaluate the printability. It is shown that DLPA is independent of the substrate and can be used to compare the printabilities from different inks. Both 3D‐PLA and DLPA can be correlated to the rheological behavior of the ink through ink rheology analysis (IRA). Finally, this research defined the design space for DIW by benchmarking the minimum and maximum particle loadings for printable composite inks.