Fully Crosslinked Poly[cyclotriphosphazene‐co‐(4,4′‐sulfonyldiphenol)] Microspheres via Precipitation Polymerization and Their Superior Thermal Properties

Fully crosslinked, stable poly[cyclotriphosphazene‐ co ‐(4,4′‐sulfonyldiphenol)] (PZS) microspheres have been prepared via the polycondensation between hexachlorocyclotriphosphazene and 4,4′‐sulfonyldiphenol by precipitation polymerization. The diameter of the PZS microspheres ranged from 0.6 to 1.0 µm with the specific surface area of the microspheres ranging from 11.7 to 10.1 m 2 · g −1 . The formation of the non‐porous microspheres was observed to obey an oligomeric species absorbing mechanism. The fully crosslinked chemical structure of the PZS microspheres were determined by IR, CP/MAS NMR, XRD, and EDX. No glass‐transition temperature was observed and the onset of the thermal‐degradation temperature was 542 °C. Thermal stability of the PZS microspheres by the precipitation polycondensation was significantly improved as compared with crosslinked microspheres produced by addition polymerizations. magnified image