Polymers with Sulfur(VI)−Nitrogen−Phosphorus Backbones: Synthesis, Characterization, and Properties of Fluoroalkoxy-Substituted Poly(thionylphosphazenes)

Reaction of the halogenated poly(thionylphosphazene) [NSOCl(NPCl 2 ) 2 ] n ( 2a ), which possesses a novel S(VI)−N−P backbone, with 2, 3, and 4 equiv of Na[OCH 2 CF 3 ], followed by excess n BuNH 2, afforded mixed-substituent poly[alkoxy(amino)thionylphosphazenes] [NSO(NH n Bu)(NPR 2 ) 2 ] n ( 6 ) ( a, R = 51% OCH 2 CF 3, 49% NH n Bu; b, R = 76% OCH 2 CF 3, 24% NH n Bu; c, R = 95% OCH 2 CF 3, 5% NH n Bu) in which the polymers were regioselectively substituted with trifluoroethoxy substituents only at phosphorus and not at sulfur. The resulting moisture stable polymers were structurally characterized by 31 P, 1 H, 13 C, and 19 F NMR spectroscopy. Molecular weights were in the range M w = 3.3 × 10 4 to 1.4 × 10 5 and M n = 1.9 × 10 4 to 8.2 × 10 4 according to GPC analysis in THF versus polystyrene standards. The thermal transition behavior was investigated by DSC, glass transition temperatures ( T g 's) ranged from −30 to −14 °C, and no melt transitions were detected. Analysis of these new polymers by TGA showed that they were stable to weight loss up to ca. 250 °C under nitrogen at a heating rate of 10 °C/min.