Poly(vinylphosphonate)s as macromolecular flame retardants for polycarbonate

A series of poly(dialkyl vinylphosphonate)s (PDAVPs) have recently been reported to be available via rare earth metal-mediated group transfer polymerization (REM-GTP). We extend the existing portfolio of polyvinylphosphonates (PVPs) by presenting poly(ditolyl vinylphosphonate) (PDTVP) as the first example of a poly(diaryl vinylphosphonate) (PDArVP). Thermogravimetric analyses revealed that, for PDTVP, in contrast to the selected PDAVPs, side group cleavage does not occur. Instead, thermal decomposition takes place in a one-step mechanism at high temperatures above 350 °C. A series of PDAVPs and PDTVP were tested for their performance as flame-retardant additives (FRA) as well as flame-retardant coatings (FRC) for polycarbonate (PC). We thereby found that PDTVP is a promising FRA, because of its high thermal stability and its compatibility with polycarbonate. Poly(diisopropyl vinylphosphonate) (PDIVP) shows excellent performance as an FRC, because it forms a stable, blistered crust of poly(vinylphosphonic acid) (PVPA) upon flame treatment.