Grafting Behavior\nof Amine Ligands for Surface Modification\nof MXene

Abstract

Surface modification to improve the oxidation stability\nand dispersibility\nof MXene in diverse organic media is a facile strategy for broadening\nits application. Among the various ligands that can be grafted on\nthe MXene surface, oleylamine (OAm), with amine functionalities, is\nan advantageous candidate owing to its strong interactions and commercial\nviability. OAms are grafted onto MXene through covalent bonds induced\nby nucleophilic reactions and H bonds in liquid interface reactions\nat room temperature. In addition, this grafting behavior of the ligand\nwas characterized by a reduction in the slope with an increase in\nthe ligand concentration (<i>C</i>_l), confirming\nthat the OAms were grafted via Langmuir-like behavior, and the monolayer\nof OAms was developed via two distinct steps (I: lying-down phase;\nII: ordered monolayer). MXene nanosheets modified by OAm (OAm-MX)\nare highly dispersible in a wide range of organic solvents owing to\nthe alkyl chain of the OAms, which induces hydrophobic properties\non the surface of MXene. The OAm-MX dispersion exhibits outstanding\noxidation and dispersion stability and remarkable coating performance\non a wide range of substrates owing to their excellent solution processability.\nTherefore, this study provides fundamental insights into the adsorption\nbehavior and interaction between amine ligands and MXene nanosheets\nfor the surface chemistry of MXene.