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Electrospinning of cellulose acetate (CA) was studied in relation to factors of solvent composition, size of spinnerete orifice, viscosity, and molecular weight. It was found that cellulose acetate nanofibers were obtained from solvent mixture N,N-dimethylacetamide (DMAc)/acetone with volume ratio of 2:1 and 1:2. Beaded nanofibers were more likely formed from solvent 2:1 DMAc/acetone, whereas bead-free CA nanofibers were produced at lower CA concentration in 1:2 DMAc/acetone. The size of spinnerete orifice showed no significant effect on the mean diameter of CA nanofiber, but small size of spinnerete orifice often resulted in nanofibers with large fiber size distribution. With respect to the effect of molecular weight on electrospinning, nanofibers of CA-398-3 (M w ¼ 3:0 Â 10 4) had wide size distribution of 90-790 nm with large amounts of big spindle-like beads along fibers. The diameters of nanofibers from CA-398-6 (M w ¼ 3:5 Â 10 4) were in the range of 90-430 nm with a few conical shape beads on fiber. In the case of CA-398-10 (M w ¼ 4:0 Â 10 4), its nanofiber diameters increased to 90-550 nm without noticeable bead defects. The water contact angles of nanofibers of CA-398-3, CA-398-6 and CA-398-10 were 81 , 50.5 and 40.4 , respectively, suggesting the orientation of hydrophobic and hydrophilic groups on the very outer fiber surface got changed when CA fiber size is down to nanometer range. The interconnected pore volume of CA nanofibrous membranes is tripled with CA molecular weight increasing from 3:0 Â 10 4 to 4:0 Â 10 4 .

In this paper, we fabricate ZnO nanofibers and nanoparticles through electrospinning precursor solution zinc acetate(ZnAc)/cellulose acetate(CA) in mixed‐solvent N,N‐dimethylformamide/acetone. Depending on the posttreatment of precursor ZnAc/CA composite nanofibers, both ZnO nanofibers and nanoparticles were synthesized after calcination of precursor nanofibers. The morphology and crystal structure of the ZnO nanofiber and nanoparticle were characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and X‐ray diffraction. It was found that the mean diameter of the ZnO nanofiber and nanoparticle was ca. 78 and 30 nm, respectively. The photo‐degradation of dye molecules such as Rhodamine B and acid fuchsin catalyzed by the ZnO nanofiber and nanoparticle was evaluated under the irradiation of visible light. Both morphological ZnO species showed strong photocatalytic activity. However, the ZnO nanofiber in the form of nanofibrous mats showed much higher efficiency than the nanoparticle although the latter has a smaller size than the former. The porous structure of ZnO nanofibrous mats is believed to improve the contacting surface areas between the catalyst and the dye molecules, while the aggregation of ZnO nanoparticle in the solution lowers the photocatalytic efficiency.

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