Surface coordination of black phosphorene for excellent stability, flame retardancy and thermal conductivity in epoxy resin

Black phosphorus (BP) are shining for its promising properties. Due to the instability and agglomeration problem, the surface coordination strategy is a key point in practical applications. Herein, a ruthenium sulfonate ligand is synthesized to coordinate black phosphorus (BP) nanosheets. By virtue of Ru-P coordination, the lone pair electrons in BP are occupied, thus the RuL3@BP displays excellent stability in environment and different solvents. Subsequently, the resulting RuL3@BP is added into epoxy resin (EP) to fabricate EP nanocomposites. RuL3@BP can effectively enhance the dispersibility of BP in EP due to the surface coordination. When the RuL3@BP is added into epoxy in an amount of 3 wt%, the char yield is distinctly improved by 96.83%, which is ascribed to the cooperative catalytic charring effect between BP and RuL3. EP/RuL3@BP nanocomposites can easily pass the UL-94 V-0 rating, and its limiting oxygen index (LOI) value rises by 26.72%. The peak of heat release rate (PHRR) is decreased by 62.21% and the total heat release (THR) reduces by 35.22%, which is assigned to the restriction of heat transfer and inhibition of flammable gas by the dense char residues. The smoke production and diffusion of thermal pyrolysis gases are dramatically suppressed in the combustion. Meanwhile, owing to strong interfacial interactions between RuL3@BP and EP, EP nanocomposites filled with 3 wt% RuL3@BP exhibit a high thermal conductivity of 0.376 W m−1 K−1, which is enhanced by 52.23% and 65.64% compared with that of EP/BP composite (0.247 W m−1 K−1) and pure EP (0.227 W m−1 K−1), respectively. This surface coordination strategy provides a novel approach for fabricating advanced-performance nanocomposites.