Distinctive stability of a free-standing monolayer clay mineral nanosheet <i>via</i> transmission electron microscopy

Akita, Ikumi; Ishida, Yohei; Yonezawa, Tetsu

doi:10.1039/d0cp04659k

Cited by 6 publications

(8 citation statements)

References 47 publications

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“…They reported that high temperature and pressure were required as high-energy sources to separate the layers. Additionally, Akita and co-workers 22 and Brito et al 23 found that centrifugation and annealing processes were necessary to achieve a single-layered clay. Clearly, perfect exfoliation methods are poorly understood, although several mechanisms have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular exfoliation of layer silicate clay by novel cationic pillar[5]arene intercalants

Kakuta

Baba

Yamagishi

et al. 2021

Sci Rep

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Clays are multi-layered inorganic materials that can be used to prepare nanocomposite fillers. Because the multi-layered structure is thermodynamically stable, it is difficult to change a multi-layered material into single layers to improve its dispersity. Previously, clays were modified with dodecylammonium cations to promote complexation with nylon 6, nylon 66, polypropylene, polyethylene, polystyrene, and polycaprolactone to increase the mechanical strength (and/or thermal stability) of the composite material; however, complete exfoliation could not be achieved in these composites. In this study, pillar[5]arenes are synthesized and functionalized with ten cationic substituents as novel intercalants for modifying bentonite clay, which is a multi-layered metal-cation-containing silicate. The pillar[5]arenes exfoliate the clay by forming polyrotaxanes with poly(ethylene glycol) through host–guest interactions.

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Section: Introductionmentioning

confidence: 99%

Supramolecular exfoliation of layer silicate clay by novel cationic pillar[5]arene intercalants

Kakuta

Baba

Yamagishi

et al. 2021

Sci Rep

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“…In addition to the bright contrast of the Pt atoms, the clay mineral nanosheets were observed stably and exhibited the characteristic periodic hexagonal contrast pattern of pristine clay mineral nanosheets. 21,22 These observations demonstrated that Pt atoms are a valid marker for ADF−STEM imaging of guest molecules assembled on a clay mineral nanosheet, as well as on simpler substrates such as graphene. [13][14][15] The Fourier transform (Figure 3d) corresponding to the medium magnification ADF-STEM image of the monolayer region (Figure 3c) revealed that the in-plane distance was similar to previously reported values for the (hk0) facet of montmorillonite.…”

Section: Resultsmentioning

confidence: 91%

“…Stable atomic-scale imaging of monolayer clay mineral nanosheets via ADF-STEM was recently reported for the first time by the current authors. 21,22 The present study aimed to directly image single organic molecules and supramolecular assemblies on monolayer clay mineral nanosheets using heavy metal atom markers. Electrostatic interactions are a weak non-covalent interaction, and enabled strong fixation of each organic molecule on the ionic 2D nanosheet supports.…”

Section: Introductionmentioning

confidence: 99%

Direct Imaging of Individual Organic Molecules in Supramolecular Assembly Strongly Fixed via Multivalent Electrostatic Interactions

2021

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Recent developments in electron microscopy and novel techniques for the precise control of low-dimensional substrate materials have led to the emergence of direct imaging of organic molecules. However, supramolecular assemblies constructed via non-covalent interactions are structurally unstable under electron bean irradiation. This study focused on a supramolecular assembly of well-isolated organic molecules based on multivalent electrostatic interactions, where anionically charged clay mineral nanosheets were used as a host material. Direct imaging of the single organic molecules and supramolecular assemblies on the monolayer clay mineral nanosheets was achieved via annular dark field scanning transmission electron microscopy using heavy metal atom markers. The versatility of multivalent electrostatic interactions for the stable fixation of organic molecules during electron microscopic imaging was demonstrated. This 2 strategy can be applied to a wide range of supramolecular systems comprising various guest molecules and host materials, thereby broadening the scope of atomic-scale imaging.

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“…The observed in-plane distances for 2D VMT are shown in Table S1 (Supporting Information) and consistent with the atomic structure expected for monoclinic alluminosilicates. [27,28] Energy-dispersive X-ray spectroscopy maps of 2D VMT show the presence of Si, Al, Mg, and Fe (Figure 1i). We use electron probe microanalysis to quantify four main components in VMT, namely SiO 2 , MgO, Al 2 O 3 , and FeOT, and their content is found to be 39.35 ± 1.29, 24.42 ± 0.99, 10.99 ± 1.24, and 6.63 ± 0.99 wt%, respectively (Table S2, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

“…The observed in‐plane distances for 2D VMT are shown in Table S1 (Supporting Information) and consistent with the atomic structure expected for monoclinic alluminosilicates. [ 27,28 ]…”

Section: Resultsmentioning

confidence: 99%

2D Functional Minerals as Sustainable Materials for Magneto‐Optics

et al. 2022

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chemical properties, 2D materials have long been the forefront of fundamental research and applications in optics and many other fields. [1][2][3][4] For instance, many efforts have been devoted to explore physical paradigms under 2D limit and enable novel optical devices, such as exciton-resonance-enabled lens, [5,6] wideband tunable mode lockers, [7,8] as well as photodetectors and harmonic generators in terahertz regime. [2,9] Noteworthy, together with recently reported 2D ferromagnets, [10][11][12] 2D materials based magneto-optics have attracted great attentions nowadays. Categorized by the interaction between material and incident light under magnetic field, four main magnetooptical effects are investigated commonly, namely the Zeeman effect, Faraday effect, magneto-optical Kerr effect, and Cotton-Mouton effect, in which 2D materials are recognized as promising matters. [13] Among these four magneto-optical effects, the Cotton-Mouton effect is of great benefits for transmitted light modulation in a see-through manner, with the potential applications ranging from sub-micron-scale dynamic light modulators to meter-scale displayable windows in future society. [14,15] The current electro-optical technologies based on liquid crystals face Liquid crystal devices using organic molecules are nowadays widely used to modulate transmitted light, but this technology still suffers from relatively weak response, high cost, toxicity and environmental concerns, and cannot fully meet the demand of future sustainable society. Here, an alternative approach to color-tunable optical devices, which is based on sustainable inorganic liquid crystals derived from 2D mineral materials abundant in nature, is described. The prototypical 2D mineral of vermiculite is massively produced by a green method, possessing size-to-thickness aspect ratios of >10 3 , inplane magnetization of >10 emu g −1 , and an optical bandgap of >3 eV. These characteristics endow 2D vermiculite with sensitive magneto-birefringence response, been several orders of magnitude larger than organic counterparts, as well as capability of broad-spectrum modulation. The finding consequently permits the fabrication of various magnetochromic or mechanochromic devices with low or even zero-energy consumption during operation. This work creates opportunities for the application of sustainable materials in advanced optics.

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Distinctive stability of a free-standing monolayer clay mineral nanosheet via transmission electron microscopy

Abstract: Among 2D materials, clay mineral nanosheets have been extensively studied owing to their specific features, such as high surface charge and large surface area. Recently, we reported a stable free-standing...

Cited by 6 publications

References 47 publications

Supramolecular exfoliation of layer silicate clay by novel cationic pillar[5]arene intercalants

Supramolecular exfoliation of layer silicate clay by novel cationic pillar[5]arene intercalants

Direct Imaging of Individual Organic Molecules in Supramolecular Assembly Strongly Fixed via Multivalent Electrostatic Interactions

2D Functional Minerals as Sustainable Materials for Magneto‐Optics

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