Efficient Delamination and Dispersion of 2D MXenes in Organic Solvents for Fabrication of Polymer Nanocomposites

MXenes, a family of two-dimensional (2D) transition metal carbides and nitrides, have attracted significant attention in recent years for their unique optical, electronic, and chemical properties, to name a few. These nanomaterials have a general formula of M<i>_n</i>₊₁X<i>_n</i>T<i>_x</i> where M is a transition metal, X is carbon and/or nitrogen, and T<i>_x</i> represents a variety of surface terminations. MXenes can be tailored for an incredibly broad array of applications, but are still often hindered by manufacturing, stability, and mechanical challenges. Many of these challenges can be overcome by integrating the 2D material into polymer matrices, leading to composites with distinct properties that can serve specific or multiple functions. To date, only a small portion of MXene research has been focused on polymer composites. Several hurdles exist for crafting high performance composites, including uniform distribution of flakes and interfacial compatibility with certain polymers, specifically hydrophobic ones. Current methods for compositing nanoparticles with polymers typically involve blending the two materials in an organic solvent, but dispersing the MXene in this medium either involves complex processing or lengthy sonication that can greatly reduce the average flake size and deteriorate properties. Herein, a more efficient approach to delaminating multilayer Ti₃C₂T<i>_x</i> MXene in an organic solvent is proposed, forming stable colloidal solutions that can be used to process composites with highly uniform flake distribution. This delamination method requires little more work than typical methods for obtaining single-layer MXene flakes and does not require any sonication or surface functionalization to improve interfacial compatibility and dispersion in a hydrophobic polymer matrix. Certain organic solvents such as propylene carbonate are highly effective in forming stable MXene solutions as well as enhancing formation of electroactive crystalline phases in polymers like PVDF. The properties of MXene-PVDF composites made through this process are examined through several characterization techniques, and potential applications of similar composite structures are explored.