Preparation of Polyimide@Polypyrrole/Palladium Hollow Composites with Applications in Catalysis

Abstract

Polyimide based hollow composites were successfully prepared by combining the situ and template methods together. Firstly, the complete words (PPy) shell was covered on the surface of polystyrene nanoparticles, then the polyamide acid and PdCl₂ were covered on the surface of the materials after the calcination. Finally, PI@ PPy/Pd hollow composites were obtained by a chemical process. The structure and composition of composites were characterized by scanning electron microscopy X-ray diffraction, thermo gravimetric analyzer and differential scanning calorimeter, respectively. Palladium (Pd) nanoparticles were densely and uniformly anchored on the surface of PPy shell due to the coordination interaction between amino groups on PPy backbone and Pd²⁺ ions. They are ideal candidates as nanoreactors for heterogeneous catalysis due to their special structure. The catalytic performance of PI@ PPy/Pd hollow composites were studied by the reduction of NaBH₄ as a reducing agent. The catalytic performance of composites was characterized by ultraviolet and visible spectrophotometer. The PI@PPy/Pd composites showed excellent catalytic performance in the reduction of methylene blue with sodium borohydride as reducing agent. The dye completely turned colorless as seen within 2.0 minutes.