Preparation, Structure And Antibacterial Activities Of Silver/Polymer Nanocomposites

Silver (Ag) nanoparticle is a kind of high-performance metallic antimicrobial agents with security and durability. Compounding Ag nanoparticles with polymer could not only improve their dispersability but also provide with or enhance the antimicrobial properties of polymer materials.In the present studys, Ag nanocolloids were synthesized in a room-temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]·BF4). And then Ag/polystyrene (PS) core/shell nanoparticles were prepared via in situ polymerization in the [BMIM]·BF4/ethanol mixed solvent. In the process of styrene polymerization, the strong sorption between Ag and [BMIM]·BF4 prevented Ag nanoparticles from aggregation, and made them disperse uniformly. Ag nanoparticles were finally embedded in PS.Ag/chitosan (CS) composite colloids were synthesized by liquid-phase chemical reduction and then Ag/CS-g-methylmethacrylate (MMA) composite was prepared by graft polymerization. The results showed that Ag nanoparticles hindered the graft polymerization of CS with MMA, which resulted in the decrease of the graft percentage and graft efficiency in comparison with those without Ag nanoparticles.Structural characterization and mechanism analysis verified that Ag-O bonds were formed by adsorption between CS molecules and Ag, and prevented Ag nanoparticles from aggregation through electrostatic effect and steric effect, which made Ag nanoparticles dispersed evenly in the composites. The graft copolymerization of CS with MMA was initiated on the hydroxide group of CS. After compounding with Ag nanoparticles, the thermal stability of CS and its graft product, CS-g-MMA was significantly increased in comparison with that of original CS.Ag/CS/poly(ethylene oxide) (PEO) composite fibrous membrane was produced by electrospinning. The morphologies of electrospun fibers under different electrospining conditions were analyzed by scanning electron microscope and transmission electron microscope. The results indicated that the ultrafine fibers with fine morphology could be obtained by electrospinning at the present of Ag nanoparticles, and the nanoparticles were dispersed uniformly in the electrospun fibers. The result of X-ray photoelectron spectroscopy revealed that approximately 10% of Ag element distributed on the surface of the fibrous membranes. The Ag/CS/PEO membrane showed a higher water uptake than that of CS/PEO electrospun membrane. The composite Ag/CS/PEO fibrous membranes showed better tensile properties than CS/PEO membrane due to the introduction of Ag nanoparticles, but the tensile properties got worse in wet state.Evaluation of antimicrobial activities showed that the resultant Ag nanoparticles demonstrated perfect antibacterial property, while Ag/PS core/shell nanocomposite particles displayed prolonged antibacterial effect and the Ag/CS composites existed higher antibacterial performance than Ag or CS alone. The antibacterial mechanisms of Ag nanoparticles and CS were studied. The antibacterial activities of Ag/CS based antimicrobial were displayed by the cooperation of Ag nanoparticles with CS.