Fabrication Of One-Dimensional Micro-Nanostructures Of Functional Materials And Their Properties

Nanoscale one dimensional (1D) materials have been popular in the field of nanoscience and nanotechnology due to their novel electrical transport, optical and magnetic properties, and potential applications in nanoscale elelctronic device, nanophotonics, sensors, energy storage and transform. In the past few years, a large part of these work has been focused on inorganic 1D nanomaterial systems, it is only very recently that composite 1D nanomaterials start to emerge. Composite 1D nanomaterials composed of different materials can combine the properties of these materials and even produce novel unique properties. It is well known that most of inorganic nanoparticles are difficult to process for their poor mechanical performance. However, most of the common polymers are processable but is rare in functionability. Therefore, the combination of polymers and functional nanoparticles can combine their properties. On the other hand, combination of two different materials with correlative properties may produce more excellent properties. In this thesis, attention is paid on the preparation of a series of polymer/inorganic and inorganic/inorganic composite 1D micro-nanomaterials and the study of their properties.First, we prepared PVP/PbS composite micro-nanofibers by elelctrospinning and gas-solid reaction. The dispersion of PbS nanoparticles in polymer fibers are studied. For the protection and limitation of polymer chains to the nanoparticles, PbS nanoparticles is uniform and well dispersed in polymer fibers. Based on this method, PVP/CdS composite micro-nanofibers are also prepared. The obtained CdS nanorods are well dispersed in PVP fibers. Another method has been developed to fabricate PVP/Ag2S compsite micro-nanofibers by combination sol-gel with electrospinning technique. We studied the formation of Ag2S nanospheres in the PVP fibers and their photoluminescence properties. In addition, we proposed a novel method called"polymer-inorganic solution electrospinning"method to prepare PVP/EuW10 compsoite micro-nanofibers. The results show that nanoscale EuW10 particles are well dispersed in PVP fibers, which avoid the phase separation. The composite fibers are stable and show red luminescence. The photoluminescence of the composite fibers have been studied in detail.Inorganic 1D nanomaterials can be obtained by calcination of the composite nanomaterials prepared by elelctrospinning. Using this method, PbTiO3 and WO3 micro-nanofibers are prepared. We also prepared TiO2/CdS composite micro-nanofibers by the formation of CdS nanoparticles on the surface of TiO2 micro-nanofibers using the mercaptocarboxylic acid as the joint reagent. The formation and the surface photovoltage properties of the composite fibers are studied. Conducting polymers are often used to fabricate polymer/inorganic composite micro-nanofibers. First, we prepared straight and helical PANI/CdS composite micro-nanowires by a self-assembly process. The formation conditions and mechanism have been investigated. The result shows that CdS nanoparticles are well dispersed in PANI micro-nanofibers. We also prepared PANI/Fe3O4 compsoite nanotubes by using ultrasonic irradiation technique. Under the ultrasonic irradiation, Fe3O4 nanoparticles are well dispersed. The strength of ultrasonic irradiation, the kind and concentration of dopants have all played an important role on the formation of PANI/Fe3O4 nanotubes. The formation mechanism and the electromagnetic properties of the composite nanotubes have been investigated.Polymer/inorganic composite coaxial nanocables have also been fabricated by using the electrospun inorganic micro-nanofibers. The first method is gas phase polymerization technique. First, the oxidants are adsorbed on the electrospun TiO2 micro-nanofibers. Then put the TiO2 micro-nanofibers with oxidants on the surface in the atmosphere of pyrrole to polymerize. The obtained PPy/TiO2 composite coaxial nanocables show good morphologies. This method can be also used to prepare other conducting polymers/other inorganic composite coaxial nanocables. The other method to prepare polymer/inorganic composite coaxial nanocables is the surfactant directed method. Surfactants have been proved to be an important medium to enhance the interaction between TiO2 micro-nanofibers and pyrrole monomer. By adding the oxidants, pyrrole will polymerize on the surface of TiO2 nanofibers to form PPy/TiO2 composite coaxial nanocables. By changing the content of pyrrole, the thickness of the PPy on the surface of TiO2 micro-nanofibers can be controlled.