Papers by Author: Yi Yang Zhao

Abstract: Functional self-assembled structure with well-defined shapes and dimensions are of great current interest. Porphyrins are attractive building manifold patterning for these structures because of their electronic, optical, and catalytic properties. In this paper, we report a novel technique for the assembly patterning of polymers. An Electrospinning process was used to create patterning with diameter ranging from 3 μm to 4 μm and length of up to several hundred micrometers in the presence of Zinc Porphyrin. Scanning electron microscopy (SEM), UV- visible spectra and EDX spectra were used to characterize the patterning. The results indicated that the patterning depended on the concentration of Porphyrin and the operational conditions.

Abstract: Poly(vinyl alcohol) (PVA) nanofibers containing functional ZnS nanoparticles have been successfully prepared by electrospinning technique. The ZnS/PVA mixture solution for electrospinning was obtained by reacting Zn(Ac)2 with Na2S in the PVA aqueous solution. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) analyses revealed that the morphology of the ZnS/PVA nanofibers consists of the dispersion of ZnS nanopaticles with cubic structure in PVA nanofibers. The coordinations between –OH and Zn2+ were characterized by infrared spectroscopy. The photoluminescence spectroscopy studies showed that the ZnS/PVA nanofibers had a strong blue-violet emission band at 450 nm, which may be associated with defect-related emission of the ZnS.

Abstract: The effects of an organic solvent on the electrospinning of water-soluble polyacrylamide with ultrahigh molecular weight were investigated. An organic solvent, DMF, was introduced to the polyacrylamide aqueous solution and subsequently, transparent spinning solutions were obtained. The spinning solution was electrospun at the voltage of 10 kV and the electrospun products were examined by scanning electron microscopy (SEM). Results indicated that all the electrospinning products including colloidal particles, beaded fibers and smooth fibers were fabricated in the DMF/H2O bi-component solvent and the morphology of electrospun products changed from smooth fiber to beaded fiber with the increasing amount of DMF used.