Preparation Of Ag Nanoparticles Located On Polymeric Microspheres By UV Light

Photopolymerization as distinguished from the thermal-initiated polymerization of a synthetic method will be applied to synthesize polymeric microspheres with simple equipment, low investment, security, environmental protection, easy to implement industrial production, and so on.Firstly in this paper, P(St-co-MMA) microspheres were prepared by photoinitiated dispersion copolymerization of styrene (St) with methyl methacrylate (MMA) in a mixture of ethanol and water (Vethanol/Vwater=7/3) using 2, 2-dimethoxy-2-phenylacetophenone (BDK) and polyvinylpyrrolidone (PVP) as the initiator and stabilizer, respectively. The effects on the yield and diameter of P(St-co-MMA) microspheres were studied. The structure, shape, and size distribution of microspheres were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and laser light scattering (LLS). It was found that the diameter of P(St-co-MMA) microspheres can be controlled in range from 500 to 800nm, and a yield of 70% could be obtained.In order to study photopolymerization further, P(St-co-MMA-co-AA) microspheres were prepared by photoinitiated emulsion polymerization of St, MMA and crylic acid (AA) in water using BDK or 2-hydroxy-4-(2-hydroxyethoxy)-2- methylpropiophenone (Irgacure 2959) and sodium dodecyl sulfate (SDS) as the initiator and emulsifier, respectively. The effects of initiator, amount of SDS, etc. on the yield and diameter of P(St-co-MMA-co-AA) microspheres were studied. The size and size distribution of resulting microspheres were characterized by scanning electron microscopy (SEM) and LLS. It was found that the diameter of P(St-co-MMA-co-AA) microspheres was uniform and could be controlled in range from 70 to 180nm. The yield was about 85%.Next, Ag nanoparticles were located evenly onto surface of the microspheres above with silver nitrate (AgNO3) as metal source. The ultrafine dispersed particles of Ag can be prepared via the reduction of corresponding silver ions (Ag+) by sodium borohydride (NaBH4) or ultraviolet (UV) light when the coordination interaction took place between the sivler and carbonyl. The composite microspheres were characterized by ultraviolet-visible spectroscopy (UV-vis), TEM and X-ray diffractometry (XRD). It was found that silver nanoparticles had dispersed effectively on the surface of polymeric microspheres and the mean diameter was smaller than 10 nm using NaBH4 as reductant. The composite microspheres had good antibacterial property on Staphylococcus aureus by antibacterial text; and photocatalytic degradation rate of methylene blue (MB) was about 97% with composite microspheres as catalyzer. The effects of Ag nanoparticles on the fluorescent properties of fluorescein (FL) were also investigated. With the increase of Ag nanoparticles concentrations, the fluorescence enhancement efficiency had a maximum.