Abstract: | 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 1H NMR, 31P NMR, and 29Si 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. |