Herein is reported a facile and controllable route for coating polystyrene (PS) particles with palladium nanoparticle@polypyrrole (PdNP@PPy) nanocomposites based on the “Swelling–Diffusion–Interfacial-Polymerization Method” (SDIPM). The formation of PdNP@PPy nanocomposites was achieved by using palladium chloride as the oxidant for pyrrole. The synthesized PS/PdNP@PPy nanocomposite particles were characterized extensively by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared and Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetry, and C, H, and N elemental microanalyses. Significantly, it is clearly found that highly dispersed PdNPs with small size are well embedded in the PPy shell. Moreover, the resultant PS/PdNP@PPy nanocomposite particles have a well-defined core/shell structure, and then the mass loading of PdNP@PPy nanocomposites on the surface of PS particles can be controlled simply by changing the weight ratio of pyrrole/PS. The synthesized PS/PdNP@PPy nanocomposite particles also show good catalytic activity and reusability in the reduction of p-nitrophenol by NaBH4.

•Some native starch granules had emulsifying ability.•Emulsifying ability of starch granules seemed inversely proportional to their sizes.•The emulsion stabilized by rice granule was very stable to against coalescence.•The close-packed “clumps” and dense packing of starch granules at interface were found.•The droplet surface coverage increased with the starch concentration.The surface properties of native starch, namely rice, waxy maize, wheat and potato starch were characterized by contact angle measurement, zeta-potential, and then the emulsifying ability of these native starch granules was investigated by using liquid paraffin as oil phase and starch granules as sole emulsifier. It was found that emulsions could be prepared by using rice, waxy maize and wheat starch granules as emulsifier, but not potato starch, which had no emulsifying ability even when the concentration of starch granules as high as 15 wt% relative to water phase. Rice starch was the best emulsifier among these native starches. The emulsion stabilized by rice granules proved to be stable to coalescence for several months when the starch concentration was above 3 wt% relative to water phase. With the increasing of the rice starch concentration, the sizes of droplets decreased and the stability of emulsions enhanced. The salt and pH values had no significant influence on the packing structure of native starch granules at interface.At the low starch concentrations, the droplet surface coverage also was low and particles formed monolayer close-packed “clumps”. When the starch concentration progressed, the droplet surface coverage increased and became monolayer dense packing.