Thermal behavior of novel hybrid inorganic-organic phosphazene polymers

The thermal behavior of the following systems have been investigated by TGA and XPS: the homopolymer of N3P3Cl4(CH3)(CH2C6H4CH=CH2) (1), copolymers of 1 with MMA and styrene, and copolymers of N3P3Cl4(i-C3H7) {C[OC(O)CH3]=CH2} (2) with MMA and styrene. Upon heating under TGA conditions the highest char yield (64 wt%) is found for the homopolymer of 1. The char yields for the copolymers appear to increase with increasing amounts of phosphazene incorporated. The one-step weight loss observed for the homopolymer of I can be ascribed mainly to elimination of HCl. The 1/styrene copolymers decompose in one step, indicating that HCl elimination, ring degradation, and depolymerization take place simultaneously. The 1/MMA copolymers show a two-step degradation. From XPS scans it follows that complete loss of chlorine rakes place in the first step and probably in combination with some depolymerization of MMA units. In the second step phosphazene ring degradation is observed, accompanied by further carbonization of the sample. The 2/styrene copolymers start to decompose about 100 degrees C lower than the 1/MMA copolymers, also exhibiting a two-step TGA curve. The first step can be associated with breakdown of polymer chains at the C-C linkage between inorganic monomers. In the second step depolymerization of the styrene sequences, HCl elimination, and ring degradation occur