| Ultrafine fibers with size effect are favored in the optical, electrical, magnetic and many other areas. Electrostatic spinning is cheaper and effective method to prepare ultrafine composite fibers. Electrospinning composite fibers possesses simultaneously performance of matrix and additives, and the performance will also well accommodated, which expands the applications of the polymer composite.In this paper, cellulose acetate (CA) loading of pesticide avermectin (AVM) was electrospun into release composite fibers. The release behavior of AVM from fiber was studied. Gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs) and cadmium telluride quantum dots (CdTe QDs) were compounded into CA to prepare nanofibers by the same method. The particles and fibers are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infrared spectroscopy, UV spectrophotometer, fluorescence spectrometer, etc. Finally, the transparency and SERS effect of casting membranes from the aligned fiber were studied. Specific content and research results are as follows:1. Determine the concentration of the spinning solution to provide a reference for the preparation of composite fibers. CA was dissolved in acetone and dimethyl formamide (DMF) with the volume ratio of2:1. The solution with concentration9wt%,11wt%,13wt%,15wt%and17wt%were electrospun, respectively. When the concentration9wt%, the bead shape is varied; when the concentration increased to13wt%, the ellipse is stretched along the fiber axis; when the CA concentration as high as15wt%, the number of beads stretched are reduced. So15wt%was identified as the optimal concentration.2. Preparation of sustained-release fiber and release behavior of AVM were studied. AVM accounted for0%,5%,10%,20%and30%for the amount of CA. Composite fibers with different morphologies were prepared and characterized. X-ray diffraction (XRD) analysis indicated that AVM crystallized by the influence of alignment of CA molecular chain in electrospinning. Thermal gravimetric analysis (TGA) and infrared (FT-IR) analysis showed the interaction between AVM and CA was not chemical but physical. The release process determined by the high-performance liquid chromatography (HPLC) was divided into two steps:first burst release and later slow release.3. Au NPs was prepared by sodium citrate reduction HAuCl4. Digital photos and ultraviolet and visible spectroscopy (UV-vis) analysis confirmed the synthesis and uniform particle size about20nm of Au NPs. Transmission electron microscopy (TEM) results showed that Au NPs were nearly spherical and there is no obvious aggregation. The crystallinity and stability of fibers are improved. The diameters of spun fibers are between200-300nm and become thinner with the Au NPs increasing.4. Synthesized Ag NPs were characterized by TEM, UV-vis and XRD and results showed that the diameters of Ag NPs with face-centered cubic structure were between5-15nm. Nanofibers were prepared by electrospinning solution and characterized by SEM, TEM, FT-IR and TGA. The diameters of Ag NPs uniformly distributing in fibers are between250-750nm. The degradation mechanism of fibers was changed by Ag NPs.5. CdTe QDs solution with different color was synthesized and characterized by fluorescence spectroscopy and TEM. The diameters of CdTe QDs with good fluorescence and narrow size distribution are about4nm. Fluorescent fibers with uneven diameter between200nm-1μm were prepared by electrospinning mixed solution. QDs are uniformly dispersed in the matrix and there were no significant changes in particle size and fluorescent color and brightness. With the QDs increasing, the crystallinity of the fibers was improved.6. The aligned Ag NPs/CA fibers with diameter between250-500nm were prepared and characterized. The fibers were casted into membrane by PVA solution. The membrane become from opaque to transparent because PVA filled with gap of loose fibers leading to increasing of light transmittance. Raman scattering effect of membrane enhanced because the polarization effects of aligned fibers increased along certain direction.In summary, sustained-release fibers and nanofibers have been successfully prepared by the method of electrospinning in this paper. The innovations in this research were as follows:1. The drug-release fibers were prepared by electrospinning stable solution of cellulose acetate (CA) and avermectin (AVM). AVM was dispersed well in the fibers and the release was stable, which opened a new path for the application of AVM and CA.2. Found the co-solvent of the nanoparticles and CA. Nanoparticles and CA were directly electrospun into nanofibers. The nanoparticles were steadily dispersed in fibers. A new method for preparing functional nano-fibers was provided.3. The fluorescent fibers were prepared by electrospinning the synthesized cadmium telluride quantum dots (CdTe QDs) and CA. The color of the fluorescent fibers and membrane proved the particle size of the synthesized QDs was consistent.4. Ag NPs and CA were spun into the alligned fibers, followed by casting film. The formed composite film was not only transparent but also enhanced for Raman effect, which laid the foundation for the preparation of such matrix material with the raman effect as optical and communications devices.
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