Preparation And Properties Of Polymer/Inorganic Composite Nanofibers By Electrospinning

Electrospinning technique has been proved to be a versatile and effective method formanufacturing one-dimensional nanomaterials, which has received special interest ofresearchers. Electrospinning is currently the only technique that allows the fabrication ofcontinuous fibers with diameters down to a few nanometers. The method can be applied tosynthetic and natural polymers, polymer alloys, and polymers loaded with chromophores,nanoparticles, or active agents, as well as to metals and ceramics. At the beginning of thiscentury, scientists began to prepare various inorganic, organic, inorganic/organic compositenanofibers by electrospinning method. Inorganic/organic composite nanofibers have beenapplied widely in fields as diverse as optoelectronics, biological medicine, biochemistryprotection, catalysis, efficient filtration, and sensor technology. Inorganic nanoparticles （suchas magnetic nanoparticles, quantum dots） with superparamagnetism and photoluminescenceare all related to their size effect. It is a challenging and significant task to composite thesepredominant inorganic nanoparticles with polymer and to fabricate1D nanocompositematerials with preeminent performance. On the one hand, polymer matrixs providenanoparticles a steady chemical environment and make them disperse uniformly with noaggregation, giving full play to its size effect. On the other hand, nanoparticles can makepolymer be functionalized and can get functional composite nanofiber combining excellentproperty of inorganic nanoparticles and machine processing property of polymer.Therefore, in this paper, we screened out poly（phenylene vinylene）（PPV） with excellentphotoluminescence, electroluminescence properties, poly（methyl methacrylate）（PMMA） withtransparency and mechanical property, poly（vinyl alcohol）（PVA） and gelatin（GE） withexcellent biocompatibility as polymer matrix；ZnS QDs and CdTe QDs with fluorescence,Fe₃O₄nanoparticles with superparamagnetism, SiO₂spheres as inorganic materials. Weprepared several kinds of polymer/inorganic composite nanofibers successfully by combiningin-situ composite method and wet-mixing with electrospinning technology. The properties ofnanofibers as-prepared were also studied. Our main work is as follows:（1） The PPV were synthetized by wessling method. In order to determine the optimaltechnological conditions, we investigate the influence of the basic conditions of PPV, PVA,GE, PMMA, such as concentration, conductivity, viscosity on electrospinning. At the sametime, we investigated the effect of the applied voltage, take-over distanced on the morphologyand diameter of the as-prepared nanofibers. （2） We synthetized several inorganic nanoparticles with different function by appropriatemethod. Fe₃O₄magnetic fluids were synthesized by chemical coprecipitation method in thepresence of4wt.%PVA aqueous solution. PVA was used as stabilizer and polymeric matrix.ZnS QDs with fluorescence character were synthesized by aqueous phase method and a seriesof CdTe QDs with different emission wavelength were synthesized by solvent-thermalmethod; SiO₂spheres were synthesized by modified St ber method. Furthermore, combiningwith electrospinning technique, we composited these as-prepared inorganic nanoparticles withdifferent polymer of PVA, GE, PPV, PMMA and got different functional composite nanofibersof PVA/Fe₃O₄, GE/Fe₃O₄, PMMA/CdTe QDs, PPV/ZnS QDs and PVA/SiO₂.（3） The samples’ surface morphology and internal structure were characterized by Fieldemission scanning electron microscope （FE-SEM）, High resolution transmission electronmicroscope （HR-TEM）. At the same time we analysed the influence of composition and ratioon performance of the composite nanofiber. The result showed that the composite fibers haduniform and continuous morphology, with the inorganic nanoparticles embedded in the fibersuniformly. The microstructure structure and performance of inorganic nanoparticles andcomposite nanofibers were characterized by Fourier transform infrared spectrometer （FT-IR）,X-ray diffraction （XRD）, Magnetic property measurement system （MPMS） and Thermalanalysis （TGA）. The results indicated that the Fe₃O₄nanoparticles were inverse cubic spinelstructure and as-prepared magnetic composite nanofibers exhibit a comparative highsaturation magnetization with superparamagnetism; ZnS QDs were cubic zinc blend structurewith an average diameter of3.8nm and the PL emission spectra of as-prepared PPV/ZnS QDscomposite fiber appeared obviously blue shift compared with PPV nanofibers; the diameter ofPMMA/CdTe QDs composite ultrafine fibers turned thinner with CdTe QDs concentrationincreased and as-prepared composite ultrafine fibers exhibited relatively high fluorescentintensity.