A benzoxazine surfactant exchange for atomic force microscopy characterization of two dimensional materials exfoliated in aqueous surfactant solutions

Liquid-phase exfoliation of two dimensional (2D) materials in aqueous solutions with stabilization via surfactants or polymers shows great potential for large scale production and integration into a breadth of applications. Atomic force microscopy (AFM) is able to characterize thickness and the distribution of exfoliated 2D flakes, while often encountering difficulty because of re-aggregation during sample preparation. Herein, we report a surfactant exchange method with a benzoxazine surfactant for AFM sample preparation. Stable dispersions of 2D materials in chloroform could be obtained by switching a range of commonly used surfactants to this benzoxazine surfactant. The Langmuir-Blodgett method was used and flakes were kept intact with polydispersity of thickness. This method was utilized successfully on graphene as well as boron nitride and MoS₂, and shows feasibility on other 2D materials.