Study On Preparation And Property Of The Silver Nanoparticles/polymer Composite Microspheres With Special Morphology

Poly(N-isopropylacrylamide) (PNIPAAm) and poly(N-vinylacetamide) (PNVA) macromonomers with a vinyl benzyl group at the end of the polymer chains were synthesized by free radical polymerization and end capping reaction, respectively. By using the synthesized macromonomers as a reaction stabilizer, the macromonomer grafted polystyrene/polyacrylonitrile (PNIPAAm-g-PAN/PSt and PNVA-g-PAN/PSt) microspheres with special structures were prepared by the dispersion copolymerization of acrylonitrile (AN) and styrene (St) in mixed solvents of ethanol/water. The properties of PNIPAAm and PNVA macromonomers , such as structures, molecular weight and molecular weight distribution were characterized by Infrared Spectra (IR), Gel Permeation Chromatography (GPC) and Nuclear Magnetic Resonance (NMR). The morphologies and diameter of the microspheres were characterized by Scanning Election Microscopy (SEM).Then silver nanoparticles immobilized on the surfaces of the PNIPAAm-g-PAN/PSt and PNVA-g-PAN/PSt microspheres with special structures were prepared by in-situ reduction of Ag+ in an ethanol-water mixed solution(v/v=7/3) at proper temperature. The Ag nanoparticles/the special structured microspheres composites were characterized by Infrared Spectra (IR), UV-visible spectroscopy and transmission electron microscopy (TEM). The results show the composite materials of silver nanoparticles/microspheres are stable.The minimum average diameter of silver nanoparticles immobilized on the surfaces of the PNIPAAm-g-PAN/PSt microspheres is about 6nm and 18nm, respectively. The diameter of silver nanoparticles immobilized on the surfaces of the PNVA-g-PAN/PSt microspheres can be controlled in ranged of 2 to 5 nm.The results of antibacterial experiment on E.coli shows that the silver nanoparticles/the microspheres with special structures have antibacterial performance on GNB and GPB.