Controlled synthesis of uniform hollow polypyrrole microcapsules by a cosolvent approach

Fabrication of Polypyrrole Hollow Nanospheres by Hard-Template Method for Supercapacitor Electrode Material

Conducting polymers like polypyrrole, polyaniline, and polythiophene with nanostructures offers several advantages, such as high conductivity, a conjugated structure, and a large surface area, making them highly desirable for energy storage applications. However, the direct synthesis of conducting polymers with nanostructures poses a challenge. In this study, we employed a hard template method to fabricate polystyrene@polypyrrole (PS@PPy) core-shell nanoparticles. It is important to note that PS itself is a nonconductive material that hinders electron and ion transport, compromising the desired electrochemical properties. To overcome this limitation, the PS cores were removed using organic solvents to create hollow PPy nanospheres. We investigated six different organic solvents (cyclohexane, toluene, tetrahydrofuran, chloroform, acetone, and N,N-dimethylformamide (DMF)) for etching the PS cores. The resulting hollow PPy nanospheres showed various nanostructures, including intact, hollow, buckling, and collapsed structures, depending on the thickness of the PPy shell and the organic solvent used. PPy nanospheres synthesized with DMF demonstrated superior electrochemical properties compared to those prepared with other solvents, attributed to their highly effective PS removal efficiency, increased specific surface area, and improved charge transport efficiency. The specific capacitances of PPy nanospheres treated with DMF were as high as 350 F/g at 1 A/g. And the corresponding symmetric supercapacitor demonstrated a maximum energy density of 40 Wh/kg at a power density of 490 W/kg. These findings provide new insights into the synthesis method and energy storage mechanisms of PPy nanoparticles.

Synthesis of IrO2 decorated core-shell PS@PPyNH2 microspheres for bio-interface application

In this paper, an effective approach is demonstrated for the fabrication of IrO₂-decorated polystyrene@functionalized polypyrrole (core@shell; PS@PPyNH₂) microspheres. The synthesis begins with the preparation of monodispersive PS microspheres with a diameter of 490 nm, by a process of emulsifier-free emulsion polymerization, followed by a copolymerization process involving pyrrole and PyNH₂ monomers in a PS microsphere aqueous suspension, to produce uniform PS@PPyNH₂ microspheres with a diameter of 536 nm. The loading of 2 nm IrO₂ nanoparticles onto the PS@PPyNH₂ microspheres can be easily adjusted by tuning the pH value of the IrO₂ colloidal solution and the PS@PPyNH₂ suspension. At pH 4, we successfully obtain IrO₂-decorated PS@PPyNH₂ microspheres via electrostatic attraction and hydrogen bonding simultaneously between the negatively-charged IrO₂ nanoparticles and the positively-charged PS@PPyNH₂ microspheres. These IrO₂-decorated PS@PPyNH₂ microspheres exhibit a characteristic cyclic voltammetric profile, similar to that of an IrO₂ thin film. The charge storage capacity is 5.19 mA cm^-2, a value almost five times greater than that of PS@PPyNH₂ microspheres. In addition, these IrO₂-decorated PS@PPyNH₂ microspheres exhibit excellent cell viability and biocompatibility.