
**The True Amphipathic Nature of Pristine Graphene Flakes**
Karolina Zofia Milowska
Ikerbasque Research Fellow, Theory, CIC nanoGUNE
Graphene, due to its extraordinary electronic, thermal and mechanical
properties, holds great promise for applications ranging from optoelectronic,
through environmental to biomedical technologies. However, for many potential
large scale processing routes to efficiently manufacture and commercialize
graphene based devices, composites, coatings, membranes or inks it is
essential to understand the fundamental colloidal properties of pristine
graphene flakes. Despite significant progress in the field in recent years,
their chemical character has remained incompletely understood and there has
been no consensus whether pristine graphene flakes are typical hydrophobes
[1,2,3] or could, under certain conditions, become wettable [4,5]. We have
reinvestigated with wet-chemistry methods, optical and electron microscopies,
quantum-mechanical, molecular dynamics and Monte Carlo studies [6]. For the
first time, calculations supported by experiments have revealed that pristine
graphene flakes are 2D amphiphiles with well defined hydrophilic edges and
hydrophobic basal plane surfaces the interplay of which allows small flakes to
be utilised as surfactants. The interactions between flakes can be controlled
by varying the flake size, its thickness and the oil-to-water ratio. Our
findings reconcile all previous results on the chemical nature of graphene
flakes. Pristine graphene flakes can stabilize water/oil emulsions even under
high pressure, high temperature and in saline solutions, conditions under
which conventional surfactants fail. In addition, I will also discuss the
potential applications of graphene flakes in the area of sustainable energy
generation.
**References **
[1] W Zhao, F Wu, H Wu, G. Chen, J. Nanomater., (2010), 528235,
[2] S. Haar et al., Sci. Rep., 5 (2015) 16684,
[3] L. Xu, Jet al., J. Phys. Chem. C, 117 (2013) 10730,
[4] L. Belyaeva, et al., Adv. Mater. 30 (2018) 1703274,
[5] B. Robinson, N. Kay, O. V. Kolosov, Langmuir, 29 (2013) 7735,
[6] AW Kuziel, et al., Adv. Mater., (2020).