Abstract

Objective In recent years， with the rapid development of electronic devices toward higher integration and miniaturization， the demand for efficient thermal management has increased significantly， making effective heat dissipation one of the primary research directions. Hexagonal boron nitride nanosheets （BNNSs）， owing to their excellent thermal conductivity and electrical insulation properties， are ideal thermal management materials. However， current BNNS preparation techniques suffer from high costs， low yields， and considerable pollution. Therefore， developing a scalable BNNS production method for thermal management applications holds substantial practical significance.

Methods A composite exfoliation method was employed. Under the synergistic effect of solid-phase （pretreatment） and liquid-phase exfoliation， high-yield BNNSs were prepared in an aqueous system with stearic acid （SA）-modified aluminum oxide （Al₂O₃） as a liquid-phase exfoliation additive. This process simultaneously produced the BNNSs-Al₂O₃-SA product （hereinafter referred to as BNNSs-Al₂O₃）， which was then used as a composite filler and filled into epoxy resin （EP） to fabricate BNNSs-Al₂O₃-EP composites.

Results and Discussion During the liquid-phase ball-milling exfoliation process， Al₂O₃ not only acted as an exfoliation additive by providing mechanical grinding but also exhibited excellent amphiphilicity due to SA modification. This enabled it to continuously attach onto the surfaces of newly exfoliated BNNSs， preventing repeated stacking of delaminated BN flakes and thereby significantly improving the exfoliation efficiency. Under optimized conditions （25% Al₂O₃-SA addition， particle size of 58.68 µm， ball-milling time of 5 h， and a ball-to-material ratio of 40：1）， the prepared BNNSs achieved a yield of 17.2%， with an average lateral size of 320 nm and an average of 5 layers. Furthermore， when the filler addition reached 30% （mass fraction）， the thermal conductivity of BNNSs-Al₂O₃-EP increased to 1.25 W·m^-1·K^-1， 89% higher than Al₂O₃-EP， 67% higher than hexagonal （h）-BN-EP， and 681% higher than pure EP.

Conclusions The solid-liquid phase composite exfoliation method enables high-yield BNNSs production while avoiding post-treatment procedures and achieving effective BNNSs-Al₂O₃ integration. The resulting product could be directly used as a composite filler， synergistically enhancing the thermal conductivity of the EP matrix. This composite exfoliation method provides a novel， green， low-cost， and scalable approach for BNNSs fabrication.

Keywords： boron nitride nanosheets； aluminum oxide； ball-milling exfoliation； epoxy resin films； thermal conductivity

Get Citation: CHEN Mengda， LI Binbin， WU Wei. Aluminum oxide-assisted preparation of boron nitride nanosheets and their applications［J］. China Powder Science and Technology， 2026， 32（2）： 1-13.

DOI：10.13732/j.issn.1008-5548.2026.02.006

Received: 2025-04-18， Revised: 2025-11-04，Online: 2025-12-10。

Funding：The research was supported by the National Natural Science Foundation of China (Grant No. 22478026)

CLC No:TB44； TQ321         Type Code: A

Serial No:1008-5548（2026）02-0001-13