2D materials have proved their potential in nearly every area of material science and chemistry. Unfortunately, large‐scale production of nanosheets is not straightforward. Current methods suffer from low yield, uncontrollable defects, and requires a high‐energy input. There is always a tradeoff between high quality and high yield. In this review, the alternative is highlighted to existing methods of 2D nanosheet production – 1D dissolution, historically known as osmotic swelling. As a thermodynamically driven, and therefore spontaneous, process it provides numerous benefits such as high aspect ratio and defect‐free nanosheets with a quantitative yield. In this review, the theory behind this process is discussed, compare it with the existing methods, and highlight the key features that allow to extend 1D dissolution to different charged layered materials. Moreover, the applications in which nanosheets obtained by 1D dissolution proved to be advantageous due to their unique, processing‐related features are discussed.
Repulsive osmotic delamination is thermodynamically allowed "dissolution" of two-dimensional (2D) materials and therefore represents an attractive alternative to liquid-phase exfoliation to obtain strictly monolayered nanosheets with an appreciable aspect ratio with quantitative yield. However, osmotic delamination was so far restricted to aqueous media, severely limiting the range of accessible 2D materials. Alkali-metal intercalation compounds of MoS 2 or graphite are excluded because they cannot tolerate even traces of water. We now succeeded in extending osmotic delamination to polar and aprotic organic solvents. Upon complexation of interlayer cations of synthetic hectorite clay by crown ethers, either 15-crown-5 or 18-crown-6, steric pressure is exerted, which helps in reaching the threshold separation required to trigger osmotic delamination based on translational entropy. This way, complete delamination in water-free solvents like aprotic ethylene and propylene carbonate, N-methylformamide, N-methylacetamide, and glycerol carbonate was achieved.
Structural colors originate by constructive interference following reflection and scattering of light from nanostructures with periodicity comparable to visible light wavelengths. Bright and noniridescent structural colorations are highly desirable. Here, we demonstrate that bright noniridescence structural coloration can be easily and rapidly achieved from suspended two-dimensional nanosheets of a clay mineral. We show that brightness is enormously improved by using double clay nanosheets, thus optimizing the clay refractive index that otherwise hampers structural coloration from such systems. Intralayer distances, and thus the structural colors, can be precisely and reproducibly controlled by clay concentration and ionic strength independently, and noniridescence is readily and effortlessly obtained in this system. Embedding such clay-designed nanosheets in recyclable solid matrices could provide tunable vivid coloration and mechanical strength and stability at the same time, thus opening a previously unknown venue for sustainable structural coloration.
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