Article pubs.acs.org/IECR
Poly(vinylphosphonate)s as Macromolecular Flame Retardants for Polycarbonate Dominik Lanzinger, Stephan Salzinger, Benedikt S. Soller, and Bernhard Rieger* WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstraße 4, 85748 Garching bei München, Germany S Supporting Information *
ABSTRACT: 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.
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INTRODUCTION The global demand of polycarbonate (PC) in 2011 was estimated to be ∼3.5 million metric tons and is expected to rise to 4.5 million metric tons by the end of 2016, with 20% of the PC produced being used in electrical and electronic applications (E&E).1 Especially for these E&E applications, flame-retardant polycarbonate compositions are essential. For this purpose, usually, PC is blended with one or various flameretardant additives (FRAs) in order to obtain flame-retardant resins.2,3 The most common FRAs used in polymer resins are halogen-based, e.g., epoxy oligomers made from tetrabromobisphenol A (TBBPA), low-molecular-weight polycarbonates from TBBPA, or polybrominated trimethylphenylindanes.2,4 Although bromine-based FRAs (BrFRAs) are very compatible with PC and yield blends with good mechanical properties, they must be used in relatively high ratios (6−15 wt %) in order to achieve UL94 V-0 rating.3 Moreover, BrFRAs are critical from an environmental point of view, because some of them have been shown to be persistent and bioaccumulating5 and the combustion of BrFRA containing polymer resins leads to the formation of highly toxic dibenzo-p-dioxins and dibenzofurans.6 Another potent class of flame retardants for PC are alkylsulfonates and arlysulfonates, which can provide V-0 ratings at loadings
