Hexagonal boron nitride is well known for its unique structure and excellent physical properties, particularly in hexagonal boron nitride nanosheets (BNNSs) with high potential in multiple technological applications. However, its severe layer-by-layer aggregation and incompatibility with processing liquids or condensed phase materials pose a great challenge. Covalent functionalization of BNNSs has been a common approach to address these critical issues, yet it is extremely difficult to carry out due to the chemical inertness of BNNSs. In this study, we report a novel and general route to covalently functionalize BNNSs via a simple reduction reaction. This involves initial negative charging through effective reductive activation which enables subsequent reactions with various organic alkyl halides. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) results confirm that linear alkyl chains with varying lengths are successfully grafted onto BNNSs, which leads to matched compatibility with organic media and the exfoliation level of few-layer thickness. The increase of the alkyl chain length considerably promotes their solubility in organic solvents with iodoalkanes as the most efficient grafting agents. Incorporation of alkylated BNNSs into a polymer matrix at low filler loadings leads to significant enhancements in mechanical properties over neat polymers, suggesting their exceptional reinforcement for polymer nanocomposites. This facile and scalable reductive chemistry route is applicable to versatile chemical modifications of BNNSs with diverse functional groups and grafting agents by reactions with suitable electrophiles.

中文翻译：

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氮化硼纳米片通过还原活化共价官能化。

六方氮化硼以其独特的结构和出色的物理性能而闻名，尤其是在六方氮化硼纳米片（BNNS）中，在多种技术应用中具有很高的潜力。然而，其严重的逐层聚集以及与处理液或冷凝相材料的不相容性构成了巨大的挑战。BNNS的共价功能化已成为解决这些关键问题的常用方法，但是由于BNNS的化学惰性，很难实施。在这项研究中，我们报告了一种新颖的通用途径，可通过简单的还原反应。这涉及通过有效的还原活化作用产生的初始负电荷，该活化作用使得随后可与各种有机烷基卤化物反应。傅里叶变换红外光谱（FTIR），X射线光电子能谱（XPS）和热重分析（TGA）结果证实，长度可变的线性烷基链已成功接枝到BNNS上，从而导致与有机介质的相容性匹配以及BNP的剥离水平几层厚度。烷基链长度的增加大大提高了它们在碘代烷烃作为最有效的接枝剂时在有机溶剂中的溶解度。在低填料含量下将烷基化的BNNS掺入聚合物基质中，与纯聚合物相比，机械性能显着提高，表明它们对聚合物纳米复合材料具有非凡的增强作用。通过与合适的亲电试剂反应，这种简便且可扩展的还原化学路线适用于具有不同官能团和接枝剂的BNNS的通用化学修饰。