Synthesis of polystyrene@polypyrrole-COOH@Ag (core@shell@shell) microspheres for potential application in anisotropic conductive paste

Abstract

We demonstrate a fabrication scheme for the synthesis of conductive core-shell (core@shell) nanoparticles consisting of polystyrene (PS) microspheres in size of 613 nm with consecutive coatings of functionalized polypyrrole (PPy-COOH) and Ag. The PPy-COOH precursors undergo polymerization on PS microspheres forming PS@PPy-COOH microspheres, followed by sensitization and Ag electroless deposition to produce PS@PPy-COOH@Ag microspheres in size of 717 nm. The PPy-COOH serves as the adhesive for intimate bonding of PS and Ag. Images from scanning and transmission electron microscopes confirm a Ag coating of 41–50 nm which is consisted of clustered nanoparticles forming a mono-layered film. From X-ray diffraction pattern, the Ag adopts a polycrystalline fcc structure with grain size of 12 nm. Results from thermal gravimetric analysis indicate a Ag loading of 54 wt%. By four-point-probe, the bulk conductivity for PS@PPy-COOH@Ag is 10,170 S m−1. These microspheres show promising potential for anisotropic conductive paste.