Total-conversion, high-concentration exfoliation of two-dimensional boron nitride by paste-based sand milling strategy for massively producing high-performance nanocomposites

Abstract Due to their extraordinary properties, two-dimensional boron nitride nanosheets (BNNSs) have great promise for a wide range of applications. To progress from the laboratory to commercial applications, the key is to develop a simple process to massively produce BNNSs as well as their macroscopic materials. Herein, an extremely simple, straightforward paste-based sand-milling exfoliation strategy is developed to produce BNNSs paste on a kilogram scale from bulk hexagonal boron nitride. A total-conversion exfoliation with ultrahigh concentration (22 wt%) and production rate (1.833 g h−1), one to four orders of magnitude higher than those in previous reports, is achieved. The exfoliation does not require any assisted chemicals (strong oxidizing acids, strong alkalis, intercalants or surfactants), and thus avoids subsequent purification treatments. Further, convenient and fast paste-based processing methods including sol-gel-film transformation, doctor blading, and foam infiltration are developed to massively produce BNNSs composite materials which present outstanding mechanical, thermoconductive and flame-retardant properties. The present paste-based strategy to produce BNNSs and their composite materials has prominent advantages over conventional solution-based strategy in simplicity, yield, concentration, throughput, production rate and solvent consumption, and thus paves the way for the commercial application of BNNSs.