Self-Assembled Nanoparticle Films Based On Electrostatic Interactions And Its Application

Recently, with the developments of nanoscience and nanotechnology,nano-objects such as nanoparticles, nanotubes, nanorods and nanowires areattracting more and more research interests. Nanoparticles are nano-sized metal orsemiconductor particles in the size range of 1-100 nm. Because of the small size,Nanoparticles possess many unique properties such as quantum-size effects, smallsize effects, surface effects, etc. They can found applications in a wide range ofresearch areas. In optical, electrical and magnetic devices, nanoparticles will bemostly used in form of thin films. The Layer-by-Layer (LBL) self-assembly methoddeveloped by G. Decher is one of the most perspective new methods of thin filmdeposition, and it has been successfully applied to thin films of nanoparticles andvarious other inorganic materials, by which to prepare polyelectrolyte/nanoparticlescomposite films. Its simplicity and universality combined with the high quality ofcoatings and uniform distribution of nanoparticles opens broad perspectives for thistechnique both in research and in industry. Based on LBL method and other newmethods in colloid and surface science, we can assembly functional nanoparticles infilm structures, which may found applications in many research areas. The assemblymethods and applications of nanoparticles have been reviewed in chapter 1. We report our work on electrostatic alternative deposition of AgI and Agnanoparticles by LBL method. Firstly, using mercaptoacetic acid as the stabilizingagent, we prepared AgI nanoparticles, which are negatively charged in aqueoussolution. Then, using LBL method, we prepared PDDA/AgI nanoparticles compositefilms based on electrostatic interactions. We monitored the film deposition processesand characterized the surface structures of the films. Then, we extended the LBLself-assembly method by assembling Ag nanoparticles on the surface of SiO2nanotubes. Deposition of nanoparticles on the surface of nano-sized substrates canmodify their surface structure and chemical properties. By further deposition of Agon the surface of SiO2 nanotubes, we got continuous Ag shells on the nanotubes.Then we removed the SiO2 templates and obtained nanotubal Ag, which may foundapplications in catalysis, spectroscopy and microelectronics.