Exfoliation modification and application of hexagonal boron nitride

Hexagonal boron nitride (hBN), known as "white graphene", has excellent physical and chemical properties, such as resistance to strong acids and alkalis, oxidation resistance, high temperature resistance, high thermal conductivity and mechanical strength, lubricity and wide The band gap and so on. Because of these characteristics, it has a wide range of applications in aerospace, catalyst carriers, electronic packaging and lubricants.

However, there is still a big problem for these applications, that is, multilayer hexagonal boron nitride is relatively inert and not easy to apply, so it must be stripped and modified. This paper mainly studies the effect of different ultrasonic methods and solvents on the peeling effect of hBN, and uses the ball milling method to peel and modify the hexagonal boron nitride, and prepare the hexagonal boron nitride aerogel by hydrothermal method, and then the hexagonal nitrogen The boron aerogel is compounded with polydimethylsiloxane to form a polymer composite material with high thermal conductivity. The specific experiment content is as follows:

(1) The ultrasonic peeling method was used to peel off hBN, and the influence of various parameters of the ultrasonic peeling method (including ultrasonic method, solvent type, etc.) on the peeling effect was studied, and then the most suitable method for peeling hBN was found. Through particle size analysis, AFM, Raman, FTIR, etc., the analysis of the peeled few-layer hBN nanosheets shows that the greater the polarity of the solvent, the greater the water solubility of the surfactant, and the greater the alkalinity of the Lewis base. The greater the power, the better the peeling effect.

(2) The ball milling method was used to modify hBN, and the influence of various parameters of ball milling (including ball milling agent, ball milling method, etc.) on the modification effect was studied. The modification effect is the best during milling, and it is proved that the ball milling method can strip and modify hBN at the same time by using Raman, particle size analysis, AFM, XRD, etc.

(3) The hexagonal boron nitride aerogel was prepared by hydrothermal method and freeze-drying method, and various hydrothermal parameters (including hydrothermal temperature, hydrothermal time, crosslinking agent and hBN concentration, etc.) The effect of the gel performance indicates that the aerogel obtained by using ascorbic acid as the crosslinking agent and hydrothermally heated at 80℃ for 24h is the best, and the composite material with high thermal conductivity is prepared by compounding with PDMS. SEM and optical photos are used to illustrate the structure and performance of the aerogel, the thermal conductivity test shows that hBN aerogel can increase the thermal conductivity of the composite material, and the compression elasticity test illustrates the mechanical properties of the composite material.