A search for new 2D surfactants: TMDs, MXenes & MBenes

Emulsification of low-dimensional materials is an effective method for formation of macroscopic structures while preserving the degree of particle exfoliation, facilitating the formation of 3D self-assembled structures with novel properties. Solid emulsifiers have several advantages over the typical surfactants that are among the most prominent contaminants continuously released into the environment [1]. Such emulsions, reported by Pickering in 1907, display a high resistance to coalescence (and hence de-emulsification) over time and under elevated temperature accompanied by the optional recovery of the solids. Pickering emulsions employs solid nano- to micro-sized particles localized at the oil-water interface in place of the surfactants. Some of 2D materials commonly considered as hydrophobic in their bigger forms can stabilize water-oil emulsions [2]. In particular, it is possible to use pristine graphene flakes to prepare ultra-stable emulsions [3]. hBN, MoS2 and WS2 can also equip the emulsions [4], however, the physico-chemical mechanism behind this behaviour is unknown. Therefore, we have undertaken extensive theoretical and experimental studies into colloidal properties of transistion metal dichalcogenides, carbides and borides flakes. Our studies revealed why and how they can be used as emulsion stabilizers.

[1]10.1007/s11356-021-16483-w

[2]10.1021/nn402371c

[3]10.1002/adma.202000608

[4]10.1039/C7NR05568D