Dispersion of graphene in ethanol using a simple solvent exchange method

Zhang, Xiaoyan; Coleman, Anthony C.; Katsonis, Nathalie; Browne, Wesley R.; Wees, B. J. van; Feringa, Ben L.

doi:10.1039/c0cc02688c

Cited by 170 publications

(118 citation statements)

References 22 publications

(32 reference statements)

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“…However, the solvent (isopropanol) used for exfoliation and gelation is not suitable for screen printing purposes due to its low boiling point and high evaporation rate. Therefore, we performed an exchange [ 16,61 ] of the gel solvent from isopropanol to the methyl ether of dipropylene glycol (DPM) to prepare a suitable screen printing ink. DPM is an environmentally safe industrial solvent combining both hydrophobic and hydrophilic properties.…”

Section: Resultsmentioning

confidence: 99%

Conductive Screen Printing Inks by Gelation of Graphene Dispersions

Arapov

Rubingh

Abbel

et al. 2015

Adv Funct Materials

149

119

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vital [ 25 ] as it facilitates thick layers (of up to 100 µm) in a single pass, however, at the expense of a lower printing defi nition.Following screen printing typically posttreatments such as drying, annealing, or top-coating are employed to maximize conductivities. The conditions of post-treatment defi ne the substrate that can be used for printing. For example, ink annealing at 250 °C and higher for 30 min [ 18,24,25 ] signifi cantly limits the range of suitable substrates and fundamentally limits high speed R2R industrial realization. Thus, the design of graphene inks that meet the requirements of current R2R applications is still to be accomplished.There are several reports on the preparation of graphene-based inks comprising either graphene oxide (GO), [ 17,19,23,[27][28][29][30] or graphite exfoliated with [ 13,16,18,22,24,25 ] and without [ 20 ] surface active agents. The preparation of inks based on GO is relatively simple. However, due to the low conductivity of GO these inks require harsh post-treatments that make them less relevant to industrial applications. Liquid-phase exfoliation of graphite with or without surfactant by ultrasonication, [ 20,[31][32][33][34] or high-shear mixing [ 22,35 ] is a fl exible, and in the latter case a scalable manufacturing approach. [ 35 ] Nevertheless prolonged high shearing still requires separation of nonexfoliated graphite while the resulting dispersions consist mainly of small (<500 nm) graphene sheets. [ 33,34,36 ] Hence the quality [ 20 ] is far from the one obtained by micromechanical cleavage. [ 37 ] In contrast, expanded graphite (EG) demonstrates much better dispersibility than graphite due to signifi cantly weakened van der Waals interactions on account of an increased distance between the layers. [ 13,[38][39][40] This results in much shorter times and smaller energy input to obtain well-exfoliated concentrated dispersions of typically large (>1 µm) fl ake graphene. [ 39,41 ] Colloidal stability, however, as for the exfoliation of graphite, requires the presence of surface active agents and can be adjusted accordingly. The quality of graphene in EG depends on the precursor used for expansion. For instance, EG obtained from GO exhibits a highly defective structure, [ 41,42 ] whereas EG obtained from either donor-or acceptor-type intercalation compounds (IC) exhibits a much smaller amount of defects and, thus, is more suitable for highly conductive inks. [39][40][41] One of the approaches for ink preparation comprises stabilization of graphene dispersions by surfactants or surface active polymers on account of charge or van der Waals repulsion. This stabilization has been studied and reported by many research

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Section: Resultsmentioning

confidence: 99%

Conductive Screen Printing Inks by Gelation of Graphene Dispersions

Arapov

Rubingh

Abbel

et al. 2015

Adv Funct Materials

149

119

View full text Add to dashboard Cite

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“…[7,9] This process generates large quantities of 2-dimensional nanosheets that are stabilised against aggregation by interactions with the liquid. This can be achieved in certain solvents, [7,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] surfactant [25][26][27][28][29][30][31] or polymer solutions [32,33] where the stabilisation mechanisms are enthalpic, electrostatic and steric respectively. [34] Alternatively, both graphene and inorganic layered materials can be exfoliated by lithium intercalation based methods to give nanosheets, [35][36][37] while graphene can be exfoliated and dispersed in liquids as graphene oxide.…”

Section: Introductionmentioning

confidence: 99%

Measuring the lateral size of liquid-exfoliated nanosheets with dynamic light scattering

et al. 2013

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We have developed an in-situ method to estimate the lateral size of exfoliated nanosheets dispersed in a liquid. Using standard liquid exfoliation and size-selection techniques, we prepared a range of dispersions of graphene, MoS 2 and WS 2 nanosheets with different mean lateral sizes. The mean nanosheet length was measured using transmission electron microscopy (TEM) to vary from ~40 nm to ~1 m. These dispersions were characterised using a standard dynamic light scattering (DLS) instrument. We found a well-defined correlation between the peak of the particle size distribution as outputted by the DLS instrument and the nanosheet length as measured by TEM. This correlation is consistent with the DLS instrument outputting the radius of the sphere with volume equal to the mean nanosheet volume. This correlation allows the mean nanosheet length to be extracted from DLS data.

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“…[36][37][38][39][40][41][42][43][44][45][46][47] This work has contributed greatly to our understanding of the dispersion process, our practical approach to dispersion and the number of solvents available to graphene researchers.…”

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confidence: 99%

Liquid Exfoliation of Defect-Free Graphene

2012

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Due to its unprecedented physical properties, graphene has generated huge interest over the last 7 years. Graphene is generally fabricated in one of two ways: as very high quality sheets produced in limited quantities by micromechanical cleavage or vapour growth, or a rather defective, graphenelike material, graphene oxide, produced in large quantities. However, a growing number of applications would profit from the availability of a method to produce high quality graphene in large quantities.This Account describes recent work to develop such a processing route inspired by previous theoretical and experimental studies on the solvent-dispersion of carbon nanotubes. That work had shown that nanotubes could be effectively dispersed in solvents whose surface energy matched that of the nanotubes. We describe the application of the same approach to the exfoliation of graphite to give graphene in a range of solvents. When graphite powder is exposed to ultrasonication in the presence of a suitable solvent, the powder fragments into nanosheets, which are stabilized against aggregation by the solvent. The enthalpy of mixing is minimized for solvents with surface energies close to that of graphene (~68 mJ/m 2 ). The exfoliated nanosheets are free of defects and oxides and can be produced in large quantities. Once solvent exfoliation is possible, the process can be optimized and the nanosheets can be separated by size. The use of surfactants can also stabilize exfoliated graphene in water, where the zeta potential of the surfactant-coated graphene nanosheets controls the dispersed concentration.Liquid exfoliated graphene can be used for a range of applications: graphene dispersions as optical limiters, films of graphene flakes as transparent conductors or sensors, and exfoliated graphene as a mechanical reinforcement for polymer-based composites. Finally, we have extended this process to exfoliate other layered compounds such as BN and MoS 2 . Such materials will be important in a range of applications from thermoelectrics to battery electrodes. This liquid exfoliation technique can be applied to a wide range of materials and has the potential to be scaled up into an industrial process. We believe the coming decade will see an explosion in the applications involving liquid exfoliated two dimensional materials.J.N. Coleman, Liquid exfoliation of defect free graphene, Accounts of Chemical Research 2

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Dispersion of graphene in ethanol using a simple solvent exchange method

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Cited by 170 publications

References 22 publications

Conductive Screen Printing Inks by Gelation of Graphene Dispersions

Conductive Screen Printing Inks by Gelation of Graphene Dispersions

Measuring the lateral size of liquid-exfoliated nanosheets with dynamic light scattering

Liquid Exfoliation of Defect-Free Graphene

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