A one pot synthesis and characterization of intrinsically fluorescent cross-linked polyphosphazene nanospheres

Abstract

Novel inorganic-organic hybrid highly crosslinked and fluorescent polyphosphazene nanospheres were prepared via a one pot polycondensation polymerization method. Fluorescein and 4,4′-diaminodiphenylmethane were used as organic monomers in the synthesis of the nanospheres. The crosslinked structure of the nanospheres was formed with inorganic octachlorocyclotetraphosphazene rings. The characterization of the prepared nanospheres was performed by SEM, EDX, solid-state ³¹P-NMR, FTIR, XPS, XRD, DLS, and UV-vis techniques. The average particle size of the nanospheres was determined to be 343 nm. The fluorescence properties of the nanospheres were investigated. When they were excited at 470 nm, the nanospheres exhibited a fluorescence emission at 520 nm in ethanol. However, they did not show fluorescence emission at solid state. The nanospheres exhibited maximum emission at pH 9.0. The synthesized nanospheres have excellent photostability in 60 minutes at pH 9.0 owing to the crosslinked and inorganic-organic hybrid structure.

Graphical Abstract

Keywords:

• Fluorescence
• polyphosphazene
• nanospheres
• cross-linked
• fluorescein
• 4,4′-diaminodiphenylmethane

Disclosure statement

No potential conflict of interest was reported by the authors.