Boron nitride nanosheet (BNNS) reveals a huge potential in preparing highly flame-retardant polymer-based thermal conductive composite, but is limited by its difficult exfoliation and functionalization. Here, hexagonal boron nitride (hBN) was simultaneously exfoliated and flame-retardant functionalized into BNNS via one-step ball milling process based on the synergetic effect of mechanical shear and chemical peeling of ammonium phosphate and sodium hydroxide. Then the epoxy (EP)-based composites containing hBN or BNNS were prepared by solution blending and program-controlled curing. The possible mechanochemical reaction mechanisms were proposed according to the incorporation of density functional theory (DFT) calculations and chemical structure characteristics. As one of potential applications, the obtained flame-retardant functionalized BNNS (BNNS₁ and BNNS₂) were used as multifunctional additives for fabricating high-performance EP-based thermal conductive composites with excellent flame retardancy. As expected, the obtained EP-based composites containing only 5 wt% BNNS exhibited a superior flame retardancy with a dramatic decrease in the values of peak heat release rate (PHRR), the total heat release (THR), the smoke production rate (SPR) and the total smoke production (TSP) corresponding to 60.9%, 35.7%, 44.3% and 38.8% reductions, respectively, compared to neat EP. The dramatical enhancement in flame retardancy was mainly attributed to the catalytic charring effect and physical barrier action of flame-retardant functionalized BNNS, led to the formation of a compact and robust char layer during combustion to protect the underlying polymer. Simultaneously, due to uniform dispersion and strong interfacial adhesion, the incorporation of BNNS not only increased the thermal conduction paths by increasing specific surface area, but also reduced the interfacial thermal resistance (R_b) caused by phonon scattering, leading to an enhancement (312.4% and 397.0%) in the TC of EP/BNNS composites at 30 wt% BNNS₁ and BNNS₂, respectively.

氮化硼纳米片（BNNS）在制备高阻燃聚合物基导热复合材料方面显示出巨大潜力，但受到其难以剥离和功能化的限制。在此，基于机械剪切以及磷酸铵和氢氧化钠化学剥离的协同作用，通过一步球磨工艺同时剥落六方氮化硼（h BN）并将其阻燃化为BNNS。然后，含有h的环氧（EP）基复合材料BN或BNNS是通过溶液混合和程序控制的固化来制备的。根据密度泛函理论（DFT）计算和化学结构特征的提出，提出了可能的机械化学反应机理。作为潜在的应用之一，获得的阻燃功能化BNNS（BNNS ₁和BNNS ₂）被用作多功能添加剂，用于制造具有出色阻燃性的高性能EP基导热复合材料。如预期的那样，所获得的仅含5 wt％BNNS的EP基复合材料显示出优异的阻燃性，峰值放热率（PHRR），总放热（THR），烟气产生率（SPR）值显着降低）和总烟雾产生量（TSP）分别比纯净EP减少了60.9％，35.7％，44.3％和38.8％。阻燃性的显着提高主要归因于阻燃功能化BNNS的催化炭化作用和物理屏障作用，导致在燃烧过程中形成致密而坚固的炭层，以保护下面的聚合物。同时，R _b）由声子散射引起，分别导致BNNS ₁和BNNS ₂在30 wt％时EP / BNNS复合材料的TC增强（312.4％和397.0％）。