Synthesis, characterization, micellization and metal coordination polymerization of pentacyanoferrate-coordinated block copolymers for monodispersed soluble Prussian blue nanospheres

Abstract

Monodispersed soluble prussian blue (PB) metal-coordination nanospheres are synthesized via a confined metal coordination polymerization within the cores of block copolymer micelles. Pentacyanoferrate-coordinated block copolymers of P(4VPFe-co-4VP)-b-PDMA (P4VPFe: pentacyanoferrate coordinated poly(4-vinylpyridine); PDMA: poly(dimethylacrylamide)) were synthesized through a ligand exchange reaction of [Fe(CN)₅NH₃]³⁻ with pyridyl moieties in P4VP-b-PDMA. The polymers were isolated and characterized using UV-Vis, FT-IR, NMR and elemental analysis. In H₂O/EtOH, selective solvents for PDMA, the polymers self-assembled into monodispersed nanospheres with P(4VPFe-co-4VP) forming cores and PDMA acting as the corona. Subsequent metal coordination polymerization of Fe³⁺ with ferrate confined within the cores of the micelles led to monodispersed PB nanospheres as confirmed by DLS, TEM, HRTEM and SEM. The particles are soluble both in water and organic solvents as a result of the robust solubility of PDMA corona chains. Several parameters, including the solvent used, the concentration of the block copolymers, the amount of FeCl₃ added and the amount of water involved in the systems, have been found to be important in order to obtain well-defined monodispersed PB nanospheres.