One Dimensional Functional Nanomaterials By Electrospinning Technique And Their Property

Compared with some convensional synthesis methods for one-dimensional nanomaterials, electrospinning technique has shown obvious advantages in control of the morphologies and sizes, microstructures of nanomaterials and assembling the inorganic parts to some extent. In this dissertation, electrospinning technique was developed to synthesize free-standing and flexible surface enhanced Raman scattering (SERS) substrate, where high SERS active Ag dimers or aligned aggregates were assembled within poly (vinyl alcohol) (PVA) nanofibers with chain like arrays. Ag/TiO2 nanofibers and nanotubes were fabricated by conventional electrospinning and coaxis electrospinning, and the mechanism of SERS is composed by both the magnetic mechanism from Ag nanoparticles or aggregates and the chemical mechanism from the cooperation of TiO2 and Ag nanoparticles. Ultra-thin Te nanowires can be selectively assembled within polymer to get Te@polymer coaxial nanocables by adjusting the amount of Te nanowires and changing the sort of polymers. The main results can be summarized as follows:1. Electrospinning technique was developed to synthesize free-standing and flexible SERS substrate, where high SERS active Ag dimers or aligned aggregates are assembled within PVA nanofibers with a chain like arrays. The aggregation state of the obtained Ag nanoparticle dimers or largers, which are formed in a concentrated PVA solution, makes a significant contribution to the high sensitivity of SERS to 4-MBA molecules with enhancement factor (EF) of 109. The superiority of enhance ability of this Ag/PVA nanofibers mat is also shown in the comparison to other substrates. Furthermore, the Ag/PVA nanofibers mat would keep a good reproducibility under a low concentration of 4-MBA molecules (10-6 M) detection with the average relative standard deviation (RSD) values of the major Raman peak less than 0.07. The temporal stability of the substrate has also been demonstrated. This disposable, easy handled flexible free-standing substrate integrated the advantages including the superiority of high sensitivity, reproducibility, stability, large scale and low cost production compared with other conventional SERS substrates, implying that it is a perfect choice for practical SERS detection application.2. Ag/TiO2 nanofibers and nanotubes were fabricated by conventional electrospinning and coaxial electrospinning. The SERS signal could be changed by adjusting the molar ratio of TiO2/Ag. The surface-deposited Ag on TiO2 can injet electrons into 4-MBA molecules adsorbed on the TiO2 surface through the conduction band of TiO2 nanoprticles for the reason that the plasmon resonance absorption of Ag under incident visible laser, which made the Ag/TiO2 one-dimensional nanomaterials do better than the pure self-assembled Ag nanoparticle film. The mechanism of SERS is composed by both the magnetic mechanism from Ag nanoparticles or aggregates and the chemical mechanism from the cooperation of TiO2 and Ag nanoparticles. And the former made the most contribution to the whole SERS intensity.3. Ultra-thin Te nanowires can be selectively assembled within polymer to get Te@polymer coaxial nanocables by adjusting the amount of Te nanowires and changing the sort of polymers. In the shell of PVP and PVA, ultra-thin Te nanowires would be dispersed parallel arrays as multicore, and in the shell of PAN, ultra-thin Te nanowires could be assembled like a bundle. The number of the core parts in the nanocables would be directly adjusted by change the mount of ultra-thin Te nanowires in the electrospinning solution. The Te@polymer multicore nanocables we got had a long life time and the PL properties of ultra-thin Te nanowires were kept down in the protection of polymer.