Zhu Pengli

Preparation of monodisperse polystyrene/silver composite microspheres and their catalytic properties

This article presents a facile method for the preparation of polystyrene/silver (PS/Ag) composite microspheres. In this approach, monodisperse PS spheres were synthesized via dispersion polymerization and modified by sulfonation to obtain sulfonated PS spheres with sulfonic acid groups on the surfaces, and then adsorbed Sn2+ ions by electrostatic interaction and used as templates. PS/Ag composite microspheres were prepared successively by addition of [Ag(NH3)2]+ complex ions to the templates dispersion, adsorbing to the surfaces of templates, and then reduction of [Ag(NH3)2]+ complex ions to Ag nanoparticles by sodium potassium tartrate. The results showed that monodisperse PS spheres with sulfonic acid groups on the surfaces were coated by an incomplete and nonuniform coverage of Ag nanoparticles in the absence of Sn2+ ions. In the presence of Sn2+ ions, however, complete and uniform Ag nanoparticles coatings were obtained on the entire PS sphere. And the deposition density and size of Ag nanoparticles can be controlled by [Ag(NH3)2]+ concentration. The resulting PS/Ag composite microspheres were characterized by SEM, TEM, XRD, TGA, and UV-vis. Preliminary catalytical tests indicated these PS/Ag composite microspheres showed good catalytic properties.

Synthesis and magnetic properties of Ni-Zn ferrite @polyaniline/epoxy composites for embedded inductor applications

The development of the electronic industry and electronic technology is proceeding in the direction of miniaturization and high frequency. The embedded passives technology, as a key technology in system-in-package mode, throws new light on improving the package of the passives. Much works have been done to develop embedded passives. For inductors, Ni-Zn ferrites with soft magnetic are ideal materials for preparing the magnetic composite materials. In this study, Ni-Zn ferrite was prepared by a chemical coprecipitation method, then was oxidative polymerization of aniline in aqueous solution and made the Ni0.5Zn0.5Fe2O4@polyaniline (NZF@PANi) core-shell particles. The obtained particles were characterized by X-ray diffraction (XRD). The magnetic epoxy composites were fabricated by mixing the core-shell particles and epoxy resin matrix. The dielectric and magnetic properties of the composites were measured by impedance analyzer (Agilent E 4991 A: 1 MHz to 1 GHz). The initial complex permeability value obtained from the toroidal sample exhibit good frequency stability and the permeability loss was low. The permeability of the epoxy composite was rising from 1.4 to 2.2 with the mass fraction of the ferrite increasing in the composite from 3%–70%.