Preparation And Properties Of β-SiC/SiO₂Fibers, SiO₂and SiO₂/ZnO Hollow Nanofibers By Electrospinning

In this paper, β-SiC/SiO₂micro/nano fibers, hydrophobic β-SiC/SiO₂fibers, SiO₂and SiO₂/ZnO hollow nanofibers were obtained via electrospinning usingpolycarbosilane （PCS） and tetraethoxysilane （TEOS） as the raw materials, respectively.The influence of technological parameters on morphology of the fibers wassystematically studied, and the preparation processes were optimized. Themicrostructure, morphology and photoluminescence properties of the products werecharacterized by infrared spectrum （IR）, X-ray diffraction （XRD）, transmissionelectron microscopy （TEM）, scanning electron microscopy （SEM） and fluorescencespectrophotometer. The main contents are as follows:1. The precursor was prepared by solution electrospinning using PCS as the rawmaterial, then, β-SiC/SiO₂micro/nano fibers were obtained by curing treatment andsintering. The influence of PCS concentration, the sort and ratio of solution, additiveand curing treatment condition on morphology of the fibers and the photoluminescenceproperty were systematically studied. The results showed that the The optimizationprocess of the curing was that the precursor was cured in muffle furnace at190℃for8h, and the β-SiC/SiO₂micro/nano fibers were prepared by calcining the precursor at1200℃for2h. The morphology of the product was mainly as same as that ofprecursor. Using xylene as solvent, controlling the concentration of PCS at60%⁷0%,β-SiC/SiO₂micro fibers with smooth surface and a diameter of10μm were obtained.The diameter of β-SiC/SiO₂micro fibers reduced to1²μm by adding10wt%TBAB/DMF in the spinning solution. Using xylene and DMF as solvent, controllingthe concentration of PCS at60%⁷0%and the mass ratio of xylene and DMF at2:1, uniform β-SiC/SiO₂nanofibers with an average diameter of500nm were obtained. Thephotoluminescence spectrum showed two emission peaks at367nm and466nm forβ-SiC/SiO₂micro fibers.2. Hydrophobic β-SiC/SiO₂fibers were prepared by surface modification ofβ-SiC/SiO₂micro/nano fibers using AC-FAS as surface modifier. The influence offiber morphology on the hydrophobility and the photoluminescence properties ofmodified fibers were studied. The results showed that, the smaller the β-SiC/SiO₂fiberdiameter, and the rougher the surface, the better hydrophobility. Water contact angle ofthe modified β-SiC/SiO₂nanofibers was up to148°. The photoluminescence spectrashowed two emission peaks at338nm and410nm for hydrophobic β-SiC/SiO₂microfibers and two emission peaks at336nm and416nm for hydrophobic β-SiC/SiO₂nanofibers. It showed that the emission peak position of the photoluminescence wasslightly changed as the diameter of the fiber changed.3. Using TEOS or TEOS/ZnO as the raw materials, ethanol as solvent, PVP aspolymer template, the SiO₂hollow nanofibers and SiO₂/ZnO hollow nanofibers wereobtained by solution electrospinning. The ratio of the raw materials, the amount ofpolymer template, spinning voltage, injection rate and the amount of ZnOnanoparticles were optimized. Microstructure, morphology, specific surface area andphotoluminescence properties were investigated. The results showed that:（1） Optimum process for preparing the precursor of SiO₂hollow nanofibers wasthat the volume ratio of TEOS and ethanol was1:3, the amount of PVP was50.0⁶2.5mg·mL^-1, the injection rate was1.0¹.5mL·h-1, the applied voltage was25³0kV, thetip-to-collector distance was15cm. SiO₂hollow nanofibers with the diameter of300⁶00nm, the wall thickness of about150nm and the inner diameter of about30nmwere obtained by curing treatment and sintering. The photoluminescence spectrumshowed two emission peaks at288nm and370nm for the SiO₂hollow nanofibers.（2） Adding ZnO nanoparticles in TEOS/PVP/ethanol solution, SiO₂/ZnO hollownanofibers were prepared according to the optimum process in （1）. The influence ofthe amount of ZnO on the morphology of product was investigated principally. Theresults showed that ZnO was benefit for forming the hollow nanofibers, but it was notthe more the better. The optimized amount of ZnO was10²0mg·mL^-1. UniformSiO₂/ZnO hollow nanofibers with the smooth surface, the diameter of300⁵00nm, thewall thickness of about100nm and the inner diameter of about300nm were obtained atthe optimum process conditions. The photoluminescence spectrum showed two emission peaks at288nm and300⁵00nm for the SiO₂/ZnO hollow nanofibers.Compared with SiO₂hollow nanofibers, SiO₂/ZnO hollow nanofibers had strongerblue emission.