Paper on Rheological Characteristics of 2D Titanium Carbide (MXene) Dispersions: A Guide for Processing MXenes

Rheological Characteristics of 2D Titanium Carbide (MXene) Dispersions: A Guide for Processing MXenes

Bilen Akuzum†‡, Kathleen Maleski†, Babak Anasori† , Pavel Lelyukh†, Nicolas Javier Alvarez*§, E. Caglan Kumbur*‡, and Yury Gogotsi*†
† A. J. Drexel Nanomaterials Institute and Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
‡ Electrochemical Energy Systems Laboratory, Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, Pennsylvania 19104, United States
§ Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
ACS Nano, Article ASAP, DOI: 10.1021/acsnano.7b08889, Publication Date (Web): February 20, 2018, Copyright © 2018 American Chemical Society

Abstract

Understanding the rheological properties of two-dimensional (2D) materials in suspension is critical for the development of various solution processing and manufacturing techniques. 2D carbides and nitrides (MXenes) constitute one of the largest families of 2D materials with >20 synthesized compositions and applications already ranging from energy storage to medicine to optoelectronics. However, in spite of a report on clay-like behavior, not much is known about their rheological response. In this study, rheological behavior of single- and multilayer Ti3C2Tx in aqueous dispersions was investigated. Viscous and viscoelastic properties of MXene dispersions were studied over a variety of concentrations from colloidal dispersions to high loading slurries, showing that a multilayer MXene suspension with up to 70 wt % can exhibit flowability.

Processing guidelines for the fabrication of MXene films, coatings, and fibers have been established based on the rheological properties

Processing guidelines for the fabrication of MXene films, coatings, and fibers have been established based on the rheological properties. Surprisingly, high viscosity was observed at very low concentrations for solutions of single-layer MXene flakes. Single-layer colloidal solutions were found to exhibit partial elasticity even at the lowest tested concentrations (<0.20 mg/mL) due to the presence of strong surface charge and excellent hydrophilicity of MXene, making them amenable to fabrication at dilute concentrations. Overall, the findings of this study provide fundamental insights into the rheological response of this quickly growing 2D family of materials in aqueous environments as well as offer guidelines for processing of MXenes.

Keywords: 2D material; MXene; processing; rheology; titanium carbide