Adsorption and removal of graphene dispersants

Irin, Fahmida; Hansen, Matthew J.; Bari, Rozana; Parviz, Dorsa; Metzler, Shane D.; Bhattacharia, Sanjoy K.; Green, Micah J.

doi:10.1016/j.jcis.2015.01.058

Cited by 31 publications

(27 citation statements)

References 38 publications

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“…A very recent example has shown how to exfoliate graphite in pure water by adjusting the sonication pressure and temperature and the GR storage conditions (0.0065 mg/mL), 9 but regardless, the most common approach is to help the exfoliation in water using additives. Some studies have pursued this by exfoliation of graphite in aqueous media with, for example, pyrene derivatives, [10][11][12] anionic surfactants, 13,14 polymers, 15,16 or proteins. [15][16][17][18] Therefore, whereas GO powders can be directly dispersed in the cell culture medium (CCM) or transferred through dilution from water, 8 pristine (chemically non-modified) GR in aqueous suspension is mostly handled with its accompanying dispersant, 15,17 or (hardly ever reported) GR powders directly dispersed in CCM.…”

Section: Introductionmentioning

confidence: 99%

Production and stability of mechanochemically exfoliated graphene in water and culture media

et al. 2016

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The preparation of graphene suspensions in water, without detergents or any other additives is achieved using freeze-dried graphene powders, produced by mechanochemical exfoliation of graphite. These powders of graphene can be safely stored or shipped, and promptly dissolved in aqueous media. The suspensions are relatively stable in terms of time, with a maximum loss of ∼25% of the initial concentration at 2 h. This work provides an easy and general access to aqueous graphene suspensions of chemically non-modified graphene samples, an otherwise (almost) impossible task to achieve by other means. A detailed study of the stability of the relative dispersions is also reported.

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Section: Introductionmentioning

confidence: 99%

Production and stability of mechanochemically exfoliated graphene in water and culture media

et al. 2016

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“…Similar effects have been seen in vacuum-filtered pristine graphene films. 19 The concentration of the graphene (stably dispersed, not agglomerated) is provided in Figure 4 as a function of irradiation time. As the irradiation time progresses, the amount of destabilized graphene coming out of dispersion increases.…”

Section: Resultsmentioning

confidence: 99%

“…The ratio of PVP to graphene in the dispersion is ~12:1; our prior study demonstrated that removal techniques such as vacuum filtration can remove bulk PVP, as shown via TGA data. 19 In order to evaluate the effect of irradiation on the dispersions, we remove the bulk PVP from the colloidal suspension of graphene/PVP using vacuum filtration, followed by re-dispersion and freeze-drying (following our prior procedures). 19 We hypothesize that UV degradation occurs not only on the bulk PVP but also on the PVP that is adsorbed onto graphene surface which allows for PVP desorption; this would imply that the PVP coverage of the stabilized graphene would decrease as a function of irradiation time.…”

Section: Resultsmentioning

confidence: 99%

“…Unfortunately, the presence of these dispersants may be counterproductive in graphenebased composites and films. 19 Our prior work investigated various means of removing excess dispersants by dialysis, vacuum filtration or spray drying. 19 However, the possibility of removing bound dispersants from the graphene surface in solution is also intriguing.…”

Section: Introductionmentioning

confidence: 99%

“…19 Our prior work investigated various means of removing excess dispersants by dialysis, vacuum filtration or spray drying. 19 However, the possibility of removing bound dispersants from the graphene surface in solution is also intriguing. One possibility is the 3 photodegradation of dispersants.…”

Section: Introductionmentioning

confidence: 99%

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Photodegradation of dispersants in colloidal suspensions of pristine graphene

Hansen

Rountree

Irin

et al. 2016

Journal of Colloid and Interface Science

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We demonstrate that UV degradation can remove polymeric dispersants from the surface of colloidal pristine graphene. In particular, we investigated the irradiation of polyvinylpyrrolidone (PVP)-dispersed graphene in water; this polymer has been established as a versatile nanosheet dispersant for a range of solvents, and it undergoes photo-oxidative degradation when exposed to UV light. We find that the molecular weight of PVP decreases with irradiation time and subsequently desorbs from the graphene surface. This causes gradual destabilization of graphene and agglomeration in water. The amount of adsorbed PVP decreases by approximately 45% after 4 h of irradiation in comparison with the non-irradiated dispersion. At this point, the majority of the stable graphene nanosheets flocculate, likely because of insufficient surface coverage as indicated by thermogravimetric analysis. Graphene aggregates were characterized as a function of irradiation time by optical microscopy, UV-vis spectroscopy, Raman spectroscopy, and conductivity measurements; the data suggest that the agglomerates maintain a graphene-like (rather than graphite-like) structure. The effect is also observed for another graphene dispersant (sapogenin), which suggests that our findings can be generalized to the broader class of photodegradable dispersants.

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Controlling and Characterizing Anisotropic Nanomaterial Dispersion

Davis

Green

2017

Nanotechnology Commercialization

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Adsorption and removal of graphene dispersants

Cited by 31 publications

References 38 publications

Production and stability of mechanochemically exfoliated graphene in water and culture media

Production and stability of mechanochemically exfoliated graphene in water and culture media

Photodegradation of dispersants in colloidal suspensions of pristine graphene

Controlling and Characterizing Anisotropic Nanomaterial Dispersion

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