Covalent Surface Modification of Ti₃C₂T_x MXene with Chemically Active Polymeric Ligands Producing Highly Conductive and Ordered Microstructure Films

Abstract

As interest continues to grow in Ti3C2T x and other related MXenes, advancement in methods of manipulation of their surface functional groups beyond synthesis-based surface terminations (T x : −F, −OH, and O) can provide mechanisms to enhance solution processability as well as produce improved solid-state device architectures and coatings. Here, we report a chemically important surface modification approach in which “solvent-like” polymers, polyethylene glycol carboxylic acid (PEG6-COOH), are covalently attached onto MXenes via esterification chemistry. Surface modification of Ti3C2T x with PEG6-COOH with large ligand loading (up to 14% by mass) greatly enhances dispersibility in a wide range of nonpolar organic solvents (e.g., 2.88 mg/mL in chloroform) without oxidation of Ti3C2T x two-dimensional flakes or changes in the structure ordering. Furthermore, cooperative interactions between polymer chains improve the nanoscale assembly of uniform microstructures of stacked MXene-PEG6 flakes into ordered thin films with excellent electrical conductivity (∼16,200 S·cm–1). Most importantly, our covalent surface modification approach with ω-functionalized PEG6 ligands (ω-PEG6-COOH, where ω: −NH2, −N3, −CHCH2) allows for control over the degree of functionalization (incorporation of valency) of MXene. We believe that installing valency onto MXenes through short, ion conducting PEG ligands without compromising MXenes’ features such as solution processability, structural stability, and electrical conductivity further enhance MXenes surface chemistry tunability and performance and widens their applications.

Recent advances in noble metal MXene-based catalysts for electrocatalysis

“…Sardar and colleagues modied the surface groups of MXenes with u-PEG6-COOH organic ligands to improve their stability. 57 3. Methods for the synthesis of noble metal MXene-based electrocatalysts…”

“…Sardar and colleagues modified the surface groups of MXenes with ω-PEG6-COOH organic ligands to improve their stability. 57…”

Ti3C2Tx MXene Polymer Composites for Anticorrosion: An Overview and Perspective

“…Surface functionalization of Ti 3 C 2 T x is important to maintain its chemical stability for long-term application in anticorrosion coatings. , The attachment of organic functional groups was used to functionalize Ti 3 C 2 T x to maintain its chemical stability . A strategy that may further improve the chemical stability of Ti 3 C 2 T x is the covalent functionalization with polymer brushes . However, the grafting of polymer brushes on Ti 3 C 2 T x for its application in anticorrosion is not explored yet.…”

“…35 A strategy that may further improve the chemical stability of Ti 3 C 2 T x is the covalent functionalization with polymer brushes. 55 However, the grafting of polymer brushes on Ti 3 C 2 T x for its application in anticorrosion is not explored yet. This can be an easier task in comparison to the assembly of MXene with other 2D materials, such as graphene or hexagonal boron nitride.…”

Electrically reading a light-driven molecular switch on 2D-Ti3C2Tx MXene via molecular engineering: towards responsive MXetronics

“…The presence of reactive terminal groups (T x ) renders the MXene surfaces suitable to accommodate different architectures via a bottom-up assembly strategy, making possible to tune the properties of MXenes. [30][31][32][33][34] Such a tunability with active molecules would enable further possibilities to cover the current gap in the eld of MXetronics due to the acquisition of programmable properties.…”