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

Abstract

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.