We hypothesise that the recent discovery of nanodomains at the air-water interface can be leveraged to nano-functionalize surfaces through casting with incorporated functional species. The interfacial self-assembly of the amphiphilic molecules, 18-methyleicosanoic acid 18-MEA and 4-(tetradecyl)benzene diazonium tetrafluoroborate TDDS, at the air-water interface and cast on silicon wafer has been investigated using Langmuir-Blodgett (LB) techniques and atomic force microscopy. The impact of composition and surface pressure (SP) on the formation of nanodomains and microstructures was examined. TDDS (which can be used to modify the electronic structure of graphene) behaves as a co-surfactant in the 18-MEA film at low concentrations, facilitating the formation of homogeneous nanodomains with functional capacity. At higher TDDS concentrations, there is evidence for phase separation in the domains, and the TDDS furthermore partitions to the aqueous phase at higher pressures. By manipulating the 18-MEA:TDDS ratio and SP, regular nano-patterns can be transitioned into novel 2D structures reminiscent of 3D water-in-oil-in-water (W/O/W) analogues ("cookie systems"), offering a versatile strategy for designing nanoarchitectures with potential applications in graphene patterning.