A One-Pot Approach to Novel Cross-Linked Polyphosphazene Microspheres with Active Amino Groups

Highly cross-linked microspheres bearing active amino groups on the surface have been successfully synthesized via a single-step precipitation polymerization of hexachlorocyclotriphosphazene (HCCP) with 4,4'-diaminodiphenyl ether (ODA) in acetonitrile medium without any added surfactant. The active microspheres were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and differential scanning calorimetry (DSC). The results revealed that the active microspheres had clean surfaces and they were in the size of micrometer range, varying from 0.5 to 2.5 mu m. The accessibility of the surface amino groups to further functionalization was confirmed by the reaction of these groups with benzoxy chloride. Interestingly, the content of amino groups can be easily tailored through changing the molar ratio of HCCP to ODA. The effects of the concentration of HCCP and the monomer ratios on the morphology were also discussed.