POLY[(ARYLOXY)PHOSPHAZENES] WITH PHENYLPHENOXY AND RELATED BULKY SIDE GROUPS - SYNTHESIS, THERMAL TRANSITION BEHAVIOR, AND OPTICAL-PROPERTIES

The effect of steric hindrance on the synthesis of poly[(aryloxy) phosphazenes] that bear bulky aryloxy substituents is discussed. The syntheses of poly[(aryloxy) phosphazenes] with the general formula [NP(OAr′)x(OAr″)y]n, where OAr′ and OAr″ are phenoxy, 2-methylphenoxy, 4-methylphenoxy, 2-phenylphenoxy, 3-phenylphenoxy, 4-phenylphenoxy, 4-benzylphenoxy, 4-cumylphenoxy, and 4-tert-butylphenoxy and x + y=2, are described. These polymers were prepared by the interaction of the corresponding sodium aryloxide with poly(dichlorophosphazenes) in dioxane at 150°C in an autoclave. This procedure allows the synthesis of poly[(aryloxy)phosphazenes] with bulky side groups while avoding equilibration depolymerization. The influence of side group structural parameters on the thermal transition behaviour of the polymers is discussed.