Covalent Surface Modification of Hydrophobic Alkoxides on Ti3C2Tx MXene Nanosheets Toward Amphiphilic and Electrically Conductive Inks

Abstract

MXenes have garnered significant interest for use in conductive inks, processed either in aqueous solutions or organic solvents following surface modification. However, maintaining their electrical conductivity during dispersion across a broad range of solvents, particularly non-polar ones, has proven challenging, limiting their potential applications as conductive dispersions. Here, a straightforward method is presented for synthesizing electrically conductive and amphiphilic MXenes via surface modification. Alkoxide groups, such as ethoxide and phenoxide, are covalently attached to Ti₃C₂T_x MXene surfaces using a nucleophilic substitution mechanism, enabling stable dispersion in both polar and non-polar solvents. These alkoxide-functionalized MXenes exhibited an electrical conductivity of up to 2,700 S cm^-1 and dispersibility in non-polar solvents like toluene, surpassing previous modification approaches. Additionally, they demonstrate enhanced oxidative stability and excellent coating performance on substrates with varied surface energies. The electromagnetic interference (EMI) shielding films fabricated with these MXenes exhibited some of the highest performance among surface-modified MXenes and their composites, achieving shielding efficiency comparable to that of pristine Ti₃C₂T_x MXene films, while offering significantly improved durability. These findings may contribute to the development of improved processing approaches for MXenes, paving the way for advancements in printable and wearable electronics while addressing key challenges in MXene processing and modification.

Keywords: MXene; alkoxide; amphiphilic; conductive ink; surface modification.