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High-efficiency exfoliation of layered materials into 2D nanosheets in switchable CO2/Surfactant/H2O system.

Wang N, Xu Q, Xu S, Qi Y, Chen M, Li H, Han B - Sci Rep (2015)

Bottom Line: Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis.Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2).The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated.

View Article: PubMed Central - PubMed

Affiliation: College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052, China.

ABSTRACT
Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis. However, fully exploiting the outstanding properties will require a method for their efficient exfoliation. Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2). The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated. Moreover, we demonstrate that the exfoliated 2D nanosheets have their worthwhile applications, for example, graphene can be used to prepare conductive paper, MoS2 can be used as fluorescent label to perform cellular labelling, and BN can effectively reinforce polymers leading to the promising mechanical properties.

No MeSH data available.


Related in: MedlinePlus

A schematic diagram of the exfoliation process of layered materials in the emulsion microenvironment of CO2/PVP/H2O system.(a) CO2 molecules impregnate into the interlayers of layered materials, weakening the ineractions between the adjacent interlayers. (b,c) The phase inversion of emulsions results in curvature transition of surfactants LM-PVP and the repulsive forces driving the curvature transition delaminate ultrathin 2D nanosheets from bulk materials. (d) The 2D nanosheets disperse stably in ethanol/water mixtures after CO2 is released.
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f1: A schematic diagram of the exfoliation process of layered materials in the emulsion microenvironment of CO2/PVP/H2O system.(a) CO2 molecules impregnate into the interlayers of layered materials, weakening the ineractions between the adjacent interlayers. (b,c) The phase inversion of emulsions results in curvature transition of surfactants LM-PVP and the repulsive forces driving the curvature transition delaminate ultrathin 2D nanosheets from bulk materials. (d) The 2D nanosheets disperse stably in ethanol/water mixtures after CO2 is released.

Mentions: Figure 1 shows the schematic diagram of the exfoliation process of layered materials in the emulsions microenvironment of the CO2/surfactant/H2O system. Since PVP can adsorb on the surface of these layered materials through the strong hydrophobic interactions between PVP chains and surface of layered materials253940, we defined a conception that layered materials and PVP can combine into a whole, defined as the “block” surfactant LM-PVP (LM refer to layered materials). The hydrophilic amide groups of LM-PVP point toward the water continuous phase, whereas hydrophobic portions of LM-PVP including hydrophobic alkyl chains and the structure of layered materials exist in the interior of surfactants.


High-efficiency exfoliation of layered materials into 2D nanosheets in switchable CO2/Surfactant/H2O system.

Wang N, Xu Q, Xu S, Qi Y, Chen M, Li H, Han B - Sci Rep (2015)

A schematic diagram of the exfoliation process of layered materials in the emulsion microenvironment of CO2/PVP/H2O system.(a) CO2 molecules impregnate into the interlayers of layered materials, weakening the ineractions between the adjacent interlayers. (b,c) The phase inversion of emulsions results in curvature transition of surfactants LM-PVP and the repulsive forces driving the curvature transition delaminate ultrathin 2D nanosheets from bulk materials. (d) The 2D nanosheets disperse stably in ethanol/water mixtures after CO2 is released.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645177&req=5

f1: A schematic diagram of the exfoliation process of layered materials in the emulsion microenvironment of CO2/PVP/H2O system.(a) CO2 molecules impregnate into the interlayers of layered materials, weakening the ineractions between the adjacent interlayers. (b,c) The phase inversion of emulsions results in curvature transition of surfactants LM-PVP and the repulsive forces driving the curvature transition delaminate ultrathin 2D nanosheets from bulk materials. (d) The 2D nanosheets disperse stably in ethanol/water mixtures after CO2 is released.
Mentions: Figure 1 shows the schematic diagram of the exfoliation process of layered materials in the emulsions microenvironment of the CO2/surfactant/H2O system. Since PVP can adsorb on the surface of these layered materials through the strong hydrophobic interactions between PVP chains and surface of layered materials253940, we defined a conception that layered materials and PVP can combine into a whole, defined as the “block” surfactant LM-PVP (LM refer to layered materials). The hydrophilic amide groups of LM-PVP point toward the water continuous phase, whereas hydrophobic portions of LM-PVP including hydrophobic alkyl chains and the structure of layered materials exist in the interior of surfactants.

Bottom Line: Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis.Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2).The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated.

View Article: PubMed Central - PubMed

Affiliation: College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052, China.

ABSTRACT
Layered materials present attractive and important properties due to their two-dimensional (2D) structure, allowing potential applications including electronics, optoelectronics, and catalysis. However, fully exploiting the outstanding properties will require a method for their efficient exfoliation. Here we present that a series of layered materials can be successfully exfoliated into single- and few-layer nanosheets using the driving forces coming from the phase inversion, i.e., from micelles to reverse micelles in the emulsion microenvironment built by supercritical carbon dioxide (SC CO2). The effect of variable experimental parameters including CO2 pressure, ethanol/water ratio, and initial concentration of bulk materials on the exfoliation yield have been investigated. Moreover, we demonstrate that the exfoliated 2D nanosheets have their worthwhile applications, for example, graphene can be used to prepare conductive paper, MoS2 can be used as fluorescent label to perform cellular labelling, and BN can effectively reinforce polymers leading to the promising mechanical properties.

No MeSH data available.


Related in: MedlinePlus