Control Of Monodisperse Polymer Metal Composite Microspheres Size

Metal composite microspheres are favored by many high-precision fields due to their good designability,versatility,environmental protection and high efficiency.However,the technological monopoly of western developed countries has led to the phenomenon of high prices and less material in the international market.Therefore,domestic researchers have paid more and more attention to the preparation of metal composite microspheres.In addition to the preparation process,the most important factor that determines the performance and application range of metal composite microspheres is the matrix material.Polystyrene microspheres have excellent characteristics such as good sphericity,uniform particle size distribution and controllable size,and easy modification of the surface of microspheres.They have become the first choice of matrix materials in metal composites and have broad development prospects.Therefore,starting from the preparation of monodisperse metal composite microspheres,this paper systematically studied and optimized the preparation technology of monodisperse polymer microspheres and monodisperse metal composite microspheres.Polystyrene microspheres were prepared by dispersion polymerization.The size,dispersion and crosslinking properties of polystyrene microspheres were studied by different polymerization conditions and different amount of raw materials.The metal composite microspheres were prepared by electroless plating method,and the morphology and structure of the metal composite microspheres were studied by different pretreatment conditions,changing the amount of bath composition and adding method of bath composition.Fourier infrared spectrometer,thermogravimetric analyzer,scanning electron microscope,X-ray diffractometer,energy spectrometer,field emission scanning surface electron microscope and uxter viscometer were used to characterize the microspheres.The specific research results of this paper are as follows:Firstly,preparation of monodisperse polystyrene microspheres: using styrene(St)as monomer,azobisisobutyronitrile(AIBN)as initiator,polyvinylpyrrolidone(PVP)as stabilizer,methanol and distilled water(DW)as solvents,Polystyrene microspheres with different particle sizes were prepared,and the particle size and dispersion of the microspheres were studied from the aspects of stabilizer types,stabilizer dosage,initiator dosage,and solvent ratio.The research results show that: with the increase of initiator content and alcohol-water ratio,the particle size of polymer microspheres gradually increases,and the dispersibility also becomes better;as the amount of stabilizer increases,the dispersion of polymer microspheres becomes Well,the particle size of the polymer microspheres increases first and then decreases.PVP with a molecular weight of 24,000 serves as a stabilizer,and its dispersibility is better than PVP with a molecular weight of 10,000 and 30,000.Secondly,the effects of changes in the amount of cross-linking agent divinylbenzene(DVB)and the amount of chain transfer agent dodecyl mercaptan(TDDM)on monodisperse microstructure were studied.The experiment found that with the gradual increase of the content of the cross-linking agent,the particle size of the polymer microspheres first increased.As the content of the cross-linking agent exceeded 1wt% [wt% / St],the size of the polymer microspheres began to decrease,and the system Flocculation began to occur in the middle and a large number of small particles were produced.Adding different amounts of chain transfer agent to the system without crosslinking agent and the system containing 1wt% crosslinking agent,it was found that adding the chain transfer agent to the system without adding crosslinking agent not only increased the size of the polymer microspheres It also makes the dispersion of polymer microspheres better.The chain transfer agent was introduced into the system with the cross-linking agent,and it was found that the chain transfer agent solved the problem of poor dispersion of the cross-linked microspheres,and as the concentration of the chain transfer agent increased,the particle size of the microspheres also increased.The dispersion of particles is getting better and better.Thirdly,preparation of metal composite microspheres by electroless plating method: First,the three-step process of concentrated sulfuric acid sulfonation-tin chloride sensitization-silver nitrate activation is used to pretreat the microspheres.In the pretreatment process,by changing the sulfonation time and temperature As well as the adjustment experiment with or without sensitization process,the most suitable pretreatment conditions were obtained: the sulfonation time was 2h,the sulfonation temperature was 55 ?,and the sensitization process was the best.After that,electroless nickel plating was carried out.In the electroless plating process,the effects of main salt concentration,reducing agent concentration and addition method,and complexing agent concentration on the composite microsphere morphology and structure were investigated.The results showed that the main salt concentration was 2.7 g / L.When the concentration of the complexing agent is 2.4 g / L and the concentration of the reducing agent is 4 g / L,and the reducing agent is added to the system at 1mL / min,the surface of the obtained PS / Ni composite microspheres is the smoothest and densest.This article also breaks through the traditional activation process,using silver nitrate instead of expensive palladium chloride,and still successfully prepares nickel balls with uniform coating,which saves a lot of cost for future industrial production.