Preparation And Properties Of Water-soluble Noble Metal Nanoparticles Study

Noble metal nanoparticles (MNPs) have received considerable attention because of their special thermal, electronic, magnetic, optical and thermal properties owing to the quantum size effect, thus preparation and study of stable water-soluble MNPs has been one of attractive areas. This paper includes three parts:the first one is to synthesize monodispersed water-soluble silver nanoparticles using poly(4-styrenes-ulfonic acid-co-maleic acid) PSSMA as both a reducing agent and a protecting agent, and to do such a deep research on the mechanism. The second one is to synthesize water-soluble gold, platinum, palladium nanoparticles and silver-gold bimetallic nanostructure. The third one focues on the applications of PSSMA-stabilized MNPs, such as Layer-by-Layer assembly, Surface Enhanced Raman Scattering (SERS) and antibacterial.(1) Nearly monodisperse silver nanoparticles have been synthesized through a simple PSSMA-AgNO3 system in which PSSMA serving as both a reductant and a stabilizer. Reacting conditions, such as reacting temperature, pH value, reacting time and the mole ratio of PSSMA/AgNO3 have great influences on the morphology,size and surface structure of silver nanoparticles. The properties of optical,structure and morphology have been thoroughly studied by UV-Vis, TEM, HRTEM, XRD, and so on. Furthermore, stepwise addition of AgNO3 has been used to prepare silver nanoparticles with different size and shape. Partial oxidation of silver nanoparticles has been ovserved, either. In the end, based on the data of 1NMR and FTIR, we have proposed a novel formation mechanism of PSSMA-stabilized Ag NPs:Free-radicals formed during the reversible thermal degradation-addition polymerization of PSSMA are responsible for reducing metal ions. Segments of maleic acid play an important role in the stabilization of silver nanoparticles.(2) The simple synthetic system has been extended to prepare other noble metal nanoparticles, such as gold, platinum, palladium nanoparticles and silver-gold bimetallic nanostructures such as silver-gold alloy and gold-silver core-shell nanostructure. The essential differences in the optical properties and the formation processes of two kinds of bimetallic nanostructures have been analysed in detail.(3) The PSSMA-stabilized noble MNPs have been applied in different fields. The electronegative PSSMA-stabled silver nanoparticles and electropositive PDDA can be assembled Layer-by-Layer on quarze substrate through electrostatic interaction. UV-Vis spectra suggest that the silver nanoparticles thus we synthesized can be assembled lay-by-lay with PDDA uniformily, which have potential applications in the areas of catalysis, molecular-detection, and so on; While using Rhodamine 6G or Rhodamine B as probing moleculer, PSSMA-stabled metal nanoparticles show Surface Enhanced Raman Scattering (SERS) effect; We have found the PSSMA-stabled silver nanoparticles synthesized have good antibacterial effects toward colibacillus.