Stabilisers, such as surfactants, polymers and polyaromatic molecules, offer an effective way to produce graphene dispersions in water by Liquid Phase Exfoliation (LPE), without degrading the properties of graphene. In...
Producing
crystals of the desired form (polymorph) is currently
a challenge as nucleation is yet to be fully understood. Templated
crystallization is an efficient approach to achieve polymorph selectivity;
however, it is still unclear how to design the template to achieve
selective crystallization of specific polymorphs. More insights into
the nanoscale interactions happening during nucleation are needed.
In this work, we investigate crystallization of glycine using graphene,
with different surface chemistry, as a template. We show that graphene
induces the preferential crystallization of the metastable α-polymorph
compared to the unstable β-form at the contact region of an
evaporating droplet. Computer modeling indicates the presence of a
small amount of oxidized moieties on graphene to be responsible for
the increased stabilization of the α-form. In conclusion, our
work shows that graphene could become an attractive material for polymorph
selectivity and screening by exploiting its tunable surface chemistry.
In this work, we apply liquid cascade centrifugation
to highly
concentrated graphene dispersions produced by liquid-phase exfoliation
in water with an insoluble bis-pyrene stabilizer to obtain fractions
containing nanosheets with different lateral size distributions. The
concentration, stability, size, thickness, and the cytotoxicity profile
are studied as a function of the initial stabilizer concentration
for each fraction. Our results show that there is a critical initial
amount of stabilizer (0.4 mg/mL) above which the dispersions show
reduced concentration, stability, and biocompatibility, no matter
the lateral size of the flakes.
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