THERMAL-BEHAVIOR OF NOVEL HYBRID INORGANIC-ORGANIC PHOSPHAZENE POLYMERS

The thermal behavior of the following systems have been investigated b y TGA and XPS: the homopolymer of N3P3Cl4(CH3)(CH2C6H4CH=CH2) (1), cop olymers 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 cond itions the highest char yield (64 wt%) is found for the homopolymer of 1. The char yields for the copolymers appear to increase with increas ing amounts of phosphazene incorporated. The one-step weight loss obse rved 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 sim ultaneously. The 1/MMA copolymers show a two-step degradation. From XP S scans it follows that complete loss of chlorine rakes place in the f irst step and probably in combination with some depolymerization of MM A units. In the second step phosphazene ring degradation is observed, accompanied by further carbonization of the sample. The 2/styrene copo lymers start to decompose about 100 degrees C lower than the 1/MMA cop olymers, also exhibiting a two-step TGA curve. The first step can be a ssociated 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.