Scope and Limitations of Using Microemulsions for the Covalent Patterning of Graphene

Patterning of graphene (functionalizing some areas while leaving others intact) is challenging, as all the C atoms in the basal plane are identical, but it is also desirable for a variety of applications, like opening a bandgap in the electronic structure of graphene. Several methods have been reported to pattern graphene, but most of them are very technologically intensive. Recently, we reported the use of microemulsions as templates to pattern graphene at the μm scale. This method is very simple and in principle tunable, as emulsions of different droplet size and composition can be prepared easily. Here, we explore in detail the scope of this methodology by applying it to all the combinations of four different emulsions and three different organic reagents, and characterizing the resulting substrates exhaustively through Raman, SEM and AFM. We find that the method is general, works better when the reactive species are outside the micelles, and requires reactive species that involve short reaction times. We explore the scope and limitations of using microemulsions (MEMs) as templates to pattern graphene covalently. This methodology is very simple and can be used to obtain functionalization in either the major (out‐patterning) or the minor (in‐patterning) components of the MEM.