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Research abstract

The liquid-phase preparation process of two-dimensional (2D) nanomaterials is crucial for the low-temperature large-area assembly of flexible multifunctional devices. MXenes, a rising star in the family of 2D materials, are mainly composed of transition metal carbides, carbonitrides or nitrides, and can achieve outstanding electrical and electrochemical properties by liquid-phase preparation. Recently, the research team of Professor Sae Byeok Jo of Sungkyunkwan University and Professor Jeong Ho Cho of Yonsei University published the latest results in "Science Advances". In the liquid phase preparation process of MXene, a polymerized superdispersant was introduced (superdispersant). Efficient preparation of MXene nanosheets. Polycarboxylate (PCE), a comb-type separated "anchor-pillar structure" provides grafting space for the polymer on the MXene van der Waals surface, thus significantly weakening colloidal interactions (on the order of 103) . Ti3C2Tx MXene exhibits unprecedented dispersibility, enabling good dispersion in polar, non-polar and even ionic solvents. In addition, the tight loading of PCE in the MXene@PCE composite film enables it to maintain a high degree of stability under prolonged mechanical and humidity stress.

Graphical guide


Figure 1. Morphology and structural characterization: A) chemical structure of comb-like PCE; B) schematic diagram of MXene@PCE hybrid surface; C pure phase MXene, MXene@PCE with a mass fraction of 30% and Ti 2p, O 1s of PCE High-resolution XPS spectra with F 1S; D) high-resolution TEM images of 30 wt% MXene@PCE; E) XRD patterns of the three samples.


Figure 2. Dispersion properties in ionic solvents: A) UV-Vis-IR absorption spectra; B) Absorbance at 750 nm in different ionic solutions; C) Coulomb distribution of three samples; D) MXene@PCE average size and growth rate.


Figure 3. Dispersion characteristics in organic solvents: A) The dispersion of MXene and 30 wt% MXene@polymer in different polar and non-polar solvents; B) The relative absorbance of MXene and 30 wt% MXene@PCE Dynamic tracking; C) Reduction of Avrami precipitation rate in MXene@polymer solution.


Figure 4. EMI shielding performance and stability test: A) EMI shielding efficiency; B) shielding, absorption and emission mechanisms of MXene and MXene@PCE; C) normalized shielding efficiency of composite films under bending test; D) MXene under certain conditions Humidity stability of @PCE.

Summarize

In this paper, comb-like PCEs are introduced into MXenes to form MXene@PCE complexes, in which PAA is tightly anchored to the MXene surface, while the flexible PEG blocks provide spatial spacing in the form of semi-dilution grafts to shield Dissipate 1 nm of strong van der Waals interactions from the surface. The obtained complex has a wide Hildebrand solubility window, from 48 MPa0.5 (water) to 18.5 MPa0.5 (chloroform), and has good performance in different polar, non-polar and low-boiling organic solvents . Due to the shielding effect, the precipitation table of MXene@PCE colloids proposes a weakened Avrami process, and the possibility of aggregation in non-polar organic solvents is reduced by orders of magnitude. PCE further promotes dispersion in different high-concentration ionic solvents, including acids, bases, and artificial seawater, proving that PCE with a comb-like design is indeed a unique dispersion material. Furthermore, the compounding with polymers resulted in the MXene@PCE composite films exhibiting excellent electromagnetic shielding properties under mechanical and humidity stress. It is worth noting that the presence of polymer components leads to certain performance losses in the final material and device, such as electronic conductivity. Depending on the application, these aspects can be detrimental in practical applications and should therefore be considered as one of the key parameters to balance the unique advantages of polymer composites such as simple liquid phase preparation versus improved mechanical stability sex, etc. Further research on minimizing dispersant components and developing suitable post-treatment methods would be beneficial for obtaining better polymer-assisted dispersion methods. Based on the research in this paper, a new door is opened for the diversified processing of MXenes to meet the needs of a wider range of applications.

Literature link

DOI: 10.1126/sciadv.abl5299

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