Preparation And Properties Of Polystyrene/Ni Composite Microspheres By Electroless Plating

Polystyrene microspheres have the advantages of good sphericity,low density,high modulus of elasticity,good monodispersity and high stability.They are ideal template materials and have broad application prospects.Core-shell composite microspheres have attracted much attention due to their wide applications in catalytic materials,microelectronic devices and electronic packaging.In this paper,polystyrene microspheres were used as core materials to prepare PS/Ni composite microspheres using sodium hypophosphite and hydrazine hydrate as reducing agents,and nickel-coated composite microspheres were prepared respectively.The relationship between the catalytic performance of composite microspheres for the reduction of p-nitrophenol by sodium borohydride and the grain size of nickel coating was also studied.The composite microspheres had good catalytic performance.In the third chapter:Polystyrene microspheres with high elastic modulus and true roundness were prepared as core materials.Sulfonic acid groups with negative charge were successfully inserted on the surface of the microspheres by coarsening with concentrated sulfuric acid.Sn²⁺could be effectively adsorbed during sensitization,Pd²⁺was reduced during activation.A uniform Pd active substance was deposited on the surface of the sphere after activation.Nickel particles were deposited on the surface of microspheres by electroless plating.The effects of concentration of each component in electroless plating bath and additives on the surface morphology of nickel coating were studied.Increasing concentration of complexing agent can make the surface of nickel coating smoother and smoother.The increase of reducing agent concentration will accelerate the reaction speed of electroless nickel plating,resulting in more and more rough nickel plating.When 0.18 mM sodium dodecyl sulfate and0.17 mM cerium oxide are respectively electroless nickel plating,the surface of nickel plating is smooth and flat without bump.In the fourth chapter,in order to remove P element from electroless nickel plating layer,improve the conductivity of polystyrene/Ni composite microspheres and improve the surface smoothness of composite microspheres,hydrazine hydrate was used as a reducing agent in the electroless plating system.The effects of electroless plating temperature,main salt concentration,reductant concentration,complexing agent concentration and loading amount on the surface morphology of electroless nickel plated polystyrene microspheres were studied.In the electroless plating system with hydrazine hydrate as reducing agent,the surface of polystyrene/Ni composite microspheres was smooth.In the fifth chapter,the relationship between surface charge,surface morphology,microsphere morphology after pretreatment and coating morphology after electroless nickel plating and coarsening time was studied by coarsening polystyrene microspheres with concentrated sulfuric acid at different time.The surface charge of coarsened polystyrene microspheres decreases with the increase of coarsening time,and the active substances deposited on the surface of pre-treated polystyrene microspheres increase with the increase of coarsening time.The effect of the grain size of electroless nickel plating on the catalytic performance of sodium borohydride for the reduction of p-nitrophenol was also studied.The results showed that the smaller the grain size of nickel layer,the stronger the catalytic performance of electroless nickel plating on the surface of polystyrene microspheres for the reduction of p-nitrophenol by sodium borohydride.