In situ synthesis of polymer-modified boron nitride nanosheets via anionic polymerization

Owing to their inherent inertness, covalent functionalization of hexagonal boron nitride nanosheets (BNNSs) proves very difficult, greatly limiting their potential applications. Herein, we report an one-pot in-situ synthesis of polymer-modified boron nitride nanosheets via reductive functionalization. Negatively charged boron nitride nanosheets, generated by a smooth reductive treatment in an electron-rich environment, are directly employed as an initiator to trigger in situ anionic polymerization of methyl methacrylate (MMA) monomers, avoiding the use of complex initiators. The successful grafting of polymethyl methacrylate (PMMA) chains onto BNNS surfaces is evidenced by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Xray photoelectron spectroscopy (XPS). The functionalized boron nitride nanosheets formed via B-C bonding through this facile "grafting from" method exhibit excellent dispersibility in acetone. When used as a filler, the material shows remarkable mechanical reinforcement for polymeric composites. The reductive charge provides a simple and scalable route for versatile chemical modifications of BNNSs to tailor surface properties of BNNSs, which will find important applications in sensors, catalysis, composite coating, bioimaging and drug delivery etc.