Poly（vinyl pyrrolidone）（PVP）/Fe 3O 4 composite nanofibers were successfully prepared by using electrospinning technique.The composite nanofibers were characterized by means of TEM（transmission electron microscopy）,XRD（X-ray diffraction）and TGA（thermogravimetric analysis）.Transmission electron microscope images of the PVP/Fe3O4 nanofibers show that the Fe3O4 nanoparticles with a diameter about 10.5 nm were dispersed in PVP fiber matrices.The XRD results show that the particles in PVP fibers were indeed Fe3O4 nanoparticles.And the TGA of PVP/Fe3O4 nanofibers show that the content of Fe3O4 nanoparticles in the composite was about 36.8%（mass fraction）.The PVP/Fe3O4 nanofibers were found to be superparamagnetic.The hysteresis loop at room temperature showed a high saturated magnetization（M s=15.1 emu/g）and a low coercive force（μ c=0）.
We present an electrospray ionization technology(ESI) to fabricate Cu-core/PVA-shell nanoparticles. The transition of nanofiber-to-nanoparticle is achieved by adjusting the mass fraction of PVA shell material containing Cu nanoparticles.
An improved bulk sol-gel process was found to prepare transparent, non-cracking, highly pure and mono-component monolithic silica gels with a low volume shrinkage. HSi（OC2H5）3 was used as a gel acceleration to shorten the whole sol-gel processing time in the place of the carbonate powders in bulk sol-gel process. The mono-component silica gel monoliths prepared via the improved bulk sol-gel process possess a microporous structure and a good transmittance in the UV-Vis region, and the mass fraction of silica is 89%, the mass fraction of small molecules is 11%.
The preparation and formation mechanism of silica/polyvinylpyrrolidone（PVP）-polyacrylonitrile（PAN） coaxial nanofibers were presented in this paper. The PVP-PAN composite nanofibers were obtained via an electrospinning technique, while SiO2 nanoparticles were prepared according to a Stber method. The measurements of water contact angle（WCA）, the compared results of silica coating PVP-PAN composite nanofibers with PAN nanofibers indicate that much PVP resided on the composite nanofiber surface, which results in the occurrence of SiO2@polymer coaxial nanofibers due to the formation of hydrogen bonding between silica and composite nanofibers and subsequent adsorption of silica on the fiber surface.
Sulfated zirconia/silica(SZ/SiO2) complex nanofibers were prepared by combining electronspinning technique and sol-gel method.First,a silica sol was electrospun at a voltage of 12 kV,then the as-electrospun silica nanofibers were immersed into a sulfated zirconia sol afterwards with a thermal treatment to obtain the SZ/SiO2 complex nanofibers.These fibers were examined by SEM,TEM,FTIR, XRD and SPS.The results indicate that the SZ nanopaticles with the average diameter of about 8 nm were disspered on the surface of silica fibers which had an average diameter of about 170 nm.The complex nanofibers had an amorphous structure.The observation of the surface-related transitions at the SPS spectrum indicates the presence of positive charges on the surface of the complex fibers.
