Synthesis of Prussian Blue-Containing Polymeric Nanocapsules via Interfacial Confined Coordination in Crosslinked Miniemulsion

Herein, we describe a versatile synthetic strategy for constructing Prussian Blue (PB)-coated polymeric nanocapsules (PB@nanocapsules) with tunable sizes and controlled PB loading. A soft template was first formed from a miniemulsion composed of water/chloroform/hexadecane (94.55:5:0.2, w/w/w), using P4VP82-b-PDMAA180 as a stabilizer and varying amounts of P4VP homopolymer as a hydrophobe and additional reactive site provider. Crosslinked nanocapsules were obtained by adding 1,2-bis-(2-iodoethoxy)ethane (BIEE) as a crosslinker. The resulting nanocapsules exhibited average hydrodynamic diameters ranging from approximately 282 nm (without P4VP homopolymer) down to 58 nm (with 0.01 g P4VP homopolymer), as determined by DLS and TEM. Subsequently, sequential coordination with sodium pentacyanoammine -ferroate(II) hydrate (Na3 [Fe(CN)5NH3]), followed by the addition of FeCl3, yielded a uniform PB coating, as confirmed by the appearance of a characteristic absorption peak at 780 nm in the UV–Vis spectra and a CN stretching shift from 2060 to 2070 cm−1 in FT-IR. TEM and HAADF-STEM with EDX mapping revealed the homogeneous distribution of Fe across the nanocapsule shells. The PB loading could be further controlled by varying the Fe3+ addition (5.0 × 10−3–4.5 × 10−2 mmol), with higher loading improving thermal stability. This rational design provides a robust and generalizable platform for engineering polymer–inorganic hybrid nanostructures with tailored functionalities.