Polymers with sulfur(VI)-nitrogen-phosphorus backbones: Synthesis, characterization, and properties of atactic poly[(amino)thionylphosphazenes]

Aminolysis of the halogenated poly(thionylphosphazene) [NSOCl(NPCl2)(2)](n) (2a), which possesses a novel S(VI)-N-P backbone, with a series of primary amines NH(2)R (R = Me, Et, Pr-n, allyl, (n)Bu, (n)Hex, and Ph) afforded the hydrolytically stable poly[(amino)thionylphosphazenes] [NSO(NHR){NP(NHR)(2)}(2)](n), 4 (a, R = Me; b, R = Et; c, R = Pr-n; d, R = allyl; e, R = (n)Bu; f, R = (n)Hex; g, R = Ph) in which both the chlorine substituents at the phosphorus center and at sulfur were replaced. Treatment of 2a with a mixture of amines, NH(2)R (R = allyl and (n)Bu), yielded a series of mixed substituent copolymers 5a-5c of which 5a and 5b were thermally and UV cross-linkable. These new polymers were structurally characterized by P-31, H-1, and C-13 NMR and IR spectroscopy and by elemental analysis. The stereochemistry of the poly[(amino)thionylphosphazenes] was investigated by P-31 NMR which indicated the polymers are atactic. Molecular weights of the polymers 4a-4g and 5a-5c were in the range M(w) = 5.0 x 10(3) to 1.3 x 10(5), M(n) = 3.3 x 10(3) to 7.4 x 10(4) according to GPC analysis in THF versus polystyrene standards. An absolute value of M(w) = 1.0 x 10(5) was obtained by low-angle laser light scattering for 4e, which was approximately double that obtained by GPC (M(w) = 4.9 x 10(4)). The thermal transition behavior of the polymers was investigated by DSC. Glass transition temperatures (T-g's) of the poly[(amino)thionylphosphazenes] 4a-4g and 5a-5c were in the range of -40 to +82 degrees C. No melt transitions were detected and wide-angle X-ray scattering studies also indicated that poly[(amino)thionylphosphazenes] were amorphous. TGA analysis showed that the poly[(amino)thionylphosphazenes] were stable to weight loss up to 200-250 degrees C under nitrogen at a heating rate of 10 degrees C/min.