Electrochemically Exfoliated Functionalized Black Phosphorene and Its Polyurethane Acrylate Nanocomposites: Synthesis and Applications

Owing to its mechanical performance, thermal stability, and size effects, single or few-layer black phosphorus (BP) has the potential to prepare the polymer nanocomposites as a candidate of nanoadditives, similar to graphene. The step to realize the scalable exfoliation of single or few-layer BP nanosheets is crucial to BP applications. Herein, we utilized a facile, green, and scalable electrochemical strategy for generating cobaltous phytate-functionalized BP nanosheets (BP-EC-Exf) wherein the BP crystal served as the cathode and phytic acid served as a modifier and an electrolyte simultaneously. Moreover, high-performance polyurethane acrylate/BP-EC-Exf (PUA/BP-EC) nanocomposites are easily prepared by a convenient UV-curable strategy for the first time. Significantly, the conclusion of introducing BP-EC-Exf into the PUA matrix resulted in enhancement in mechanical properties of PUA in terms of the tensile strength (increased by 59.8%) and tensile fracture strain (increased by 88.1%), in the distinct improvement in flame retardancy of PUA in terms of the decreased peak heat release rate (reduced by 44.5%) and total heat release (decreased by 34.5%), and in lower intensities of pyrolysis products including toxic CO. Moreover, it was confirmed by X-ray diffraction and Raman spectra that the air stability of PUA/BP-EC nanocomposites was maintained after exposure to environmental conditions for 4 months. The air-stable BP nanosheets, which were wrapped and embedded in the PUA matrix, can achieve the isolation and protection effect. This modified electrochemical method toward the simultaneous exfoliation and functionalization of BP nanosheets provides an efficient approach for fabricating BP-polymer-based nanocomposites.