Recently, our group reported a novel preparation of poly(cyclotriphosphazene‐co‐4,4′‐sulfonyldiphenol) nanotubes (PZSNTs), which could be conveniently prepared in a one‐pot process at room temperature without any surfactant or other compatibilizing agent. PZSNTs were a new kind of phosphazene‐containing crosslinked polymers which attracted considerable interest for their outstanding biocompatibility, thermal stability, and flame‐retardant property. Moreover, PZSNTs which possessed inherent surface active hydroxyl groups could be directly used as a crosslinking agent to prepare polyurethane hybrid networks. PZSNTs were homogeneously dispersed in the polyurethane matrix. Tensile tests indicated that the nanocomposites were significantly reinforced by crosslinking of PZSNTs. The tensile strength was enhanced from 11.4 to 21.5 MPa while the elongation at break was almost invariable (460–430%). The storage moduli of the nanocomposites were significantly higher than that of the pure polyurethane. In terms of thermogravimetric analysis (TGA), the nanocomposites displayed an improved thermal stability. Copyright © 2010 John Wiley & Sons, Ltd.

IntroductionIn recent years, inorganic/organic hybrid materials have attracted considerable attention because of their outstanding chemical and physical properties. The hybrid materials are applied in many fields, such as optical wave guide, [1] semiconductor nanocrystals, [2] magnetic materials, [3] and bioactive materials. [4] Among them, polyphosphazene are an important class of hybrid materials because they not only have a wide range of thermal and chemical stabilities, but also can provide improved flameretardant properties to reinforced polymers. [5][6][7] The best known phosphazene materials are linear polymers with an alternating P¼N backbone; [8] however, their main disadvantage, in further widening the application of linear polyphosphazenes, is their low yield and high cost. Other kinds of phosphazene materials, having long attracted attention, are cyclolinear and cyclomatrix phosphazenes. Recently, cyclolinear phosphazene-containing polymers have been developed for a range of backbone systems including polyimides, [9] polyurethanes (PU), [10,11] and polyketones. [12] However, the complexities involved with the synthesis of cyclolinear phosphazenes severely limit their desirability. In the past decades, a series of cyclomatrix phosphazenes had been reported, [13,14] which were Novel polyurethane (PU) composites were prepared, based on hybrid inorganic/organic phosphazene-containing microspheres. The FT-IR spectra have shown that the microspheres have been linked with PU matrix. The microstructure of the composites is investigated by SEM. In comparison with PU, the glass transition temperatures and thermal stability of the composites are increased. The results from tensile testing of the composites have indicated that tensile strength is improved and elongation at break is almost invariable. The investigation on the surface properties of the composites showed that the water contact angles are obviously increased by adding 2 and 4 wt.-% microspheres to the matrix.