Chemistry Reference
In-Depth Information
Figure 6(a) shows photographs of dispersions of few-layer graphene
in nonpolar solvents. The reaction of graphene with a mixture of
concentrated H
2
SO
4
and HNO
3
gives water-soluble graphene which is
stable for several months (see Fig. 6(b)). Graphene is solubilized in
CCl
4
by interaction with organosilane and organotin reagents such as
hexadecyltrimethoxysilane (HDTMS) and dibutyldimethoxytin (DBDT)
as can be seen from Figs. 6(c) and 6(d) respectively [47].
Graphene can be functionalized through non-covalent modification
without affecting its electronic structure by wrapping with surfactants
or through Π-Π interaction with aromatic molecules such as
1-pyrenebutanoic acid succinimidyl ester (PyBS) (I) (Fig. 6(e)) and the
potassium salt of coronene tetracarboxylic acid (CS) (II).
Scheme 1. Exfoliation of few-layer graphene with CS to yield monolayer graphene-CS
composites (From reference 48).
Interaction of II with few-layer graphene causes exfoliation and
selectively solubilizing single-and double-layer graphenes in water
through molecular charge-transfer interaction [48]. Non-covalent
interaction of graphene with surfactants such as Igepal CO-890
