Construction of novel silicon-phosphorus linear polymers with DDSQ and DOPO derivatives for effective flame retardancy of PC/ABS

Two kinds of novel silicon-phosphorus linear polymers were synthesized by the hydrosilylation reaction of double-decker-shaped silsesquioxane (DDSQ) and 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO) derivatives and characterized using H-1 NMR, P-31 NMR, and Si-29 NMR. Flame-retardant polycarbonate/acrylonitric-butadiene-styrene (PC/ABS) blends were prepared with different contents of silicon-phosphorus linear polymers. The flame-retardant properties of silicon-phosphorus linear polymers as well as the morphology were investigated in detail by using thermogravimetric analysis (TGA), limiting oxygen index (LOI), (Underwriters Laboratory) UL-94, microscale combustion calorimetry (MCC), and scanning electron microscopy (SEM), respectively. The silicon-phosphorus linear polymers containing DDSQ and DOPO units can synergistically improve the flame retardancy and thermal stability of PC/ABS blends. Flame-retardant polymers with different linkers between DDSQ and phosphate units show comparable effect on the flame retardancy of PC/ABS.