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Mapping MXene Alignment under Shear : An In Situ SAXS Study of Size-Dependent Orientation Dynamics

Zhang, Jizhen ; Lynch, Peter A. ; Usman, Ken Aldren S. ; Qin, Si ; Mota-Santiago, Pablo LU and Razal, Joselito M. (2026) In ACS Nano 20(8). p.7333-7342
Abstract

Effective control over the alignment of 2D nanomaterials in solution is critical for optimizing their macroscopic properties. However, the fundamental factors governing this alignment remain poorly understood. This study addresses this gap by investigating the disorder-to-order transition states of Ti3C2Tx MXene sheets. We specifically examine the interplay among sheet sizes, concentrations, and shear rates in driving orientation. Our results reveal a strong size-dependent behavior. Large sheets (∼5 μm) at a high concentration (30 mg mL–1) spontaneously align into stable liquid crystalline phases. Conversely, small sheets (∼250 nm) require a minimum shear rate (0.11 s–1) to align... (More)

Effective control over the alignment of 2D nanomaterials in solution is critical for optimizing their macroscopic properties. However, the fundamental factors governing this alignment remain poorly understood. This study addresses this gap by investigating the disorder-to-order transition states of Ti3C2Tx MXene sheets. We specifically examine the interplay among sheet sizes, concentrations, and shear rates in driving orientation. Our results reveal a strong size-dependent behavior. Large sheets (∼5 μm) at a high concentration (30 mg mL–1) spontaneously align into stable liquid crystalline phases. Conversely, small sheets (∼250 nm) require a minimum shear rate (0.11 s–1) to align but lose order rapidly, particularly at low concentrations (e.g., 25 s at 1 mg mL–1). Fiber wet-spinning experiments further demonstrate how the shear rate directly dictates sheet alignment and, consequently, the electrical conductivity of the resulting fibers. These findings provide key insights for fabricating ordered structures from MXene dispersions and other anisotropic nanomaterials, highlighting the importance of understanding orientation dynamics to advance solution-based processing.

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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
MXene, orientation, shear rate, sheet size, small-angle X-ray scattering
in
ACS Nano
volume
20
issue
8
pages
10 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:41705519
  • scopus:105031807651
ISSN
1936-0851
DOI
10.1021/acsnano.5c22370
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2026 American Chemical Society
id
d6439c7c-4353-4f5a-8a51-dc92e7db7417
date added to LUP
2026-05-11 15:33:01
date last changed
2026-05-11 15:33:46
@article{d6439c7c-4353-4f5a-8a51-dc92e7db7417,
  abstract     = {{<p>Effective control over the alignment of 2D nanomaterials in solution is critical for optimizing their macroscopic properties. However, the fundamental factors governing this alignment remain poorly understood. This study addresses this gap by investigating the disorder-to-order transition states of Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> MXene sheets. We specifically examine the interplay among sheet sizes, concentrations, and shear rates in driving orientation. Our results reveal a strong size-dependent behavior. Large sheets (∼5 μm) at a high concentration (30 mg mL<sup>–1</sup>) spontaneously align into stable liquid crystalline phases. Conversely, small sheets (∼250 nm) require a minimum shear rate (0.11 s<sup>–1</sup>) to align but lose order rapidly, particularly at low concentrations (e.g., 25 s at 1 mg mL<sup>–1</sup>). Fiber wet-spinning experiments further demonstrate how the shear rate directly dictates sheet alignment and, consequently, the electrical conductivity of the resulting fibers. These findings provide key insights for fabricating ordered structures from MXene dispersions and other anisotropic nanomaterials, highlighting the importance of understanding orientation dynamics to advance solution-based processing.</p>}},
  author       = {{Zhang, Jizhen and Lynch, Peter A. and Usman, Ken Aldren S. and Qin, Si and Mota-Santiago, Pablo and Razal, Joselito M.}},
  issn         = {{1936-0851}},
  keywords     = {{MXene; orientation; shear rate; sheet size; small-angle X-ray scattering}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{8}},
  pages        = {{7333--7342}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{ACS Nano}},
  title        = {{Mapping MXene Alignment under Shear : An In Situ SAXS Study of Size-Dependent Orientation Dynamics}},
  url          = {{http://dx.doi.org/10.1021/acsnano.5c22370}},
  doi          = {{10.1021/acsnano.5c22370}},
  volume       = {{20}},
  year         = {{2026}},
}