Transparent, highly thermostable and flame retardant polycarbonate enabled by rod-like phosphorous-containing metal complex aggregates

It has been desirable to create flame retardant, transparent polycarbonate (PC) materials while retaining high thermostability and mechanical strength to meet its practical applications in the electrical, optical lighting, automobile and mobile fields. Unfortunately, current flame retardants offer satisfactory flame retardancy at the expense of other properties because of improper designs. For this reason, it has remained a grand challenge to achieve an integrated performance portfolio. Herein, we report rod-like phosphorus-containing metal complex aggregates (CePn) by one-step solvothermal method. The results show that the peak heat release rate (PHRR) and total smoke release (TSR) of the bulk PC are respectively reduced by 46% and 26% in the addition of 4 wt% of CePn, in addition to a desired UL-94 V-0 rating and a limiting oxygen index (LOI) of 27.3% because of dual-phase flame retardant mechanisms of CePn. Moreover, the final PC maintains a high transparency of 90.1% and a comparable tensile strength to the bulk PC. Moreover, the final PC composite shows enhanced thermal stability noticeably which is superior to that of any other reported systems. This work offers an innovative methodology for the design of flame retardants with tunable aggregated morphologies, and the creation of high-performance PC composites combining exceptional flame retardancy, transparency, thermostability and mechanical strength.