Journal of Materials Science, Vol.51, No.8, 4096-4103, 2016
Cyclotriphosphazene-containing polymeric nanotubes: synthesis, properties, and formation mechanism
Highly crosslinked, cyclotriphosphazene-containing polymer nanotubes have been successfully synthesized by polycondensation between hexachlorocyclotriphosphazene and melamine with pyridine as solution and acid-acceptor. The obtained nanotubes with rough surface, closed at one end, of lengths in several micrometers range, outer diameter in the range of 50-250 nm, and two ends of inner diameters in the range of 50-100 and 100-200 nm, respectively have been investigated by SEM and TEM. The formation mechanism has been proposed and named as self-template directing approach. In order to verify this mechanism, the products at variable stages of polymerization were traced by SEM. In addition, the melamine played a crucial role during the polymerization, guiding the formation of nanotube's structure. The nanotubes showed remarkable thermal performance with the initial decomposition temperature at 220 A degrees C and the residual is more than 40 % at 800 A degrees C. Also, the morphology of nanotubes has undergone a progress from monodispersed nanotubes, to aggregation state, and to sponge-like structure at 220, 350, and 800 A degrees C, respectively.