Water-icing-triggered scalable and controllable exfoliation of hexagonal boron nitride nanosheets

Hexagonal boron nitride nanosheets (h-BNNSs) are a functional material with excellent performance; they have broad application prospects in the field of heat dissipation of electronic devices. To achieve commercial application as soon as possible, there is an urgent need to develop a simple, controllable, and scalable method to produce high-quality h-BNNSs. Here, a scalable and controllable approach is proposed to exfoliate high-quality h-BNNSs from hexagonal boron nitride (h-BN) flakes that relies on efficient reduction of h-BNNS interlayer interaction by rapid volume expansion of water in icing. The effectiveness and feasibility of this method are verified by molecular dynamics simulations. The thickness of h-BNNSs is determined by freezing and exfoliation cycles, and monolayer h-BNNSs can be obtained after five cycles of freezing and exfoliation. The as-obtained h-BNNSs have excellent dispersibility in water, enabling versatile application as polymer additives, thermal conductive fillers, flame retardants, and more.