Poly[(vinyloxy)cyclophosphosphazenes]

The vinyloxycyclophosphazene derivatives, N3P3Cl5OCH=CH2 (1) and N4P4Cl7OCH =CH2 (6), undergo radical polymerization to produce the highly functionaliz ed homopolymers [CH(ON3P3Cl5)-CH2](n) (7) and [CH(ON4P4Cl7)CH2](n) (8). The se materials undergo a remarkable two-step thermal decomposition process. T he first step is an exothermic cross-linking reaction involving the elimina tion of HCl at modest temperatures. The activation energy for the first ste p is lower for 7 than for 8. The second step is an endothermic elimination of the ore-bridged cyclophosphazene dimer, (N3P3Cl5)(2)O. Copolymers have b een obtained from mixtures of 1 and 6. The calculated reactivity ratios sho w a preference for incorporation of 1 over 6 into the copolymers. Attempted copolymerization of 1 with styrene leads to mixtures of the respective hom opolymers. Attempts to polymerize N3P3X5OCH=CH2 [X = F(2), OCH3 (3), OCH2CF 3 (4), N(CH3)(2) (5)] lead to various outcomes including insoluble material s, oligomers, or recovery of unreacted monomer. The sensitivity of the poly merization to the nature of the phosphazene substituents has been related t o monomer electronic structure and reactivity of the exocyclic groups.