MXenes, transition metal carbides or nitrides, have gained great attention in recent years due to their high electrical conductivity and catalytic activity, hydrophilicity, and diverse surface chemistry. However, high hydrophilicity and negative ζ potential of the MXene nanosheets limit their processability and interfacial assembly. Previous examples for modifying the dispersibility and wettability of MXenes have focused on the use of organic ligands, such as alkyl amines, or covalent modification with triethoxysilanes. Here, we report a simple method to access MXene-stabilized oil-in-water emulsions by using common inorganic salts (e.g., NaCl) to flocculate the nanosheets and demonstrate the use of these Pickering emulsions to prepare capsules with shells of MXene and polymer. Ti₃C₂T_z nanosheets are used as the representative MXene. The salt-flocculated MXene nanosheets produce emulsions that are stable for days, as determined by optical microscopy imaging. The incorporation of a diisocyanate in the discontinuous oil phase and diamine in the continuous water phase led to interfacial polymerization and the formation of capsules. The capsules were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), confirming the presence of both polymer and nanosheets. The addition of ethanol to the capsules led to the removal of the toluene core and retention of the shell structure. The ability to assemble MXene nanosheets at fluid–fluid interfaces without the use of ligands or cosurfactants expands the accessible material constructs relevant for biomedical engineering, water purification, energy storage, electromagnetic electronics, catalysis, and so on.

中文翻译：

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MXene的絮凝及其作为二维二维表面活性剂用于胶囊形成

近年来，MXene，过渡金属碳化物或氮化物由于其高电导率和催化活性，亲水性以及多样的表面化学而备受关注。然而，MXene纳米片的高亲水性和负ζ电势限制了它们的可加工性和界面组装。改变MXene的分散性和润湿性的先前例子集中在有机配体例如烷基胺的使用或与三乙氧基硅烷的共价改性上。在这里，我们报告了一种通过使用常见的无机盐（例如NaCl）絮凝纳米片来获得MXene稳定的水包油乳液的简单方法，并展示了使用这些Pickering乳液制备带有MXene和聚合物壳的胶囊的方法。钛₃ C ₂ T_ž纳米片用作代表性的MXene。盐絮凝的MXene纳米片产生的乳剂可稳定几天，这是通过光学显微镜成像确定的。在不连续的油相中引入二异氰酸酯，在连续的水相中引入二胺导致界面聚合和形成胶囊。通过傅里叶变换红外（FTIR）光谱，X射线光电子能谱（XPS）和扫描电子显微镜（SEM）对胶囊进行了表征，确认了聚合物和纳米片均存在。向胶囊中添加乙醇导致甲苯核的去除和壳结构的保留。