High-throughput synthesis of cross-linked poly(cyclotriphosphazene-co-bis(aminomethyl)ferrocene) microspheres and their performance as a superparamagnetic, electrochemical, fluorescent and adsorbent material

- Ferrocene based phosphazene microspheres have been successfully synthesized.
- The diameters of the cross-linked microspheres vary from 0.3 to 1.3 μm.
- The microspheres act as a potent adsorbent for the removal of methylene blue.
- These multifunctional microspheres can possibly be used in several applications.

Ferrocenylphosphazenes have been attracting increasing attention for their special properties and potential applications. We describe here a new high-throughput synthesis of cross-linked poly(cyclotriphosphazene-co-bis(aminomethyl)ferrocene) microspheres via the polycondensation of hexachlorocyclotriphosphazene and 1,1′-di(aminomethyl)ferrocene by precipitation polymerization. The mean diameter of the microsphere varies from 0.3 to 1.3 μm, depending on the concentrations of both monomers in a calculated molar ratio. The morphology and structure of microspheres were characterized by FT-IR, SEM, EDX and TEM analyses. TG analysis demonstrated their superior thermal stability owing to the presence of high cross-linked bonding. Magnetic measurements revealed that the microspheres are superparamagnetic with a saturation magnetization of 23.7 emu g−1. The electrochemical properties of the microspheres were also examined by cyclic voltammetry and the results showed a single reversible redox process. Room-temperature photoluminescence spectra of the microspheres exhibited a strong emission peak at 405 nm. The Brunauer−Emmett−Teller (BET) pore-size distribution maximum is about 37.4 nm that leads to efficient adsorption behavior. These microspheres were found to be an excellent high capacity adsorbent for the selective cationic dye (methylene blue) removal from contaminated water. The changes in parameters, such as contact time, temperature and concentration of adsorbate were examined to study their influence on adsorption capacity. The results obtained suggest that the microspheres can effectively adsorb methylene blue with an adsorption capacity increasing from 480 to 2160 mg g−1 as the initial concentration was increased from 50 to 400 mg L−1. Owing to the superior properties and novelty of the synthesized hybrid microspheres, they can possibly be used in several applications, e.g., in catalysis, bio-assays, and electric and magnetic devices.

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