Morphology Control And Properties Study Of PVA/SF Composite Fibers Containing Ag Nanoparticles

Polymer nanocomposites containing metal nanoparticles, which possess the features of both metal nanoparticles and polymer nanofibers, are applied extensively in many fields. In this paper, the preparation process, morphology control and properties of poly (vinyl alcohol) (PVA) / silk fibroin (SF) composite fibers containing Ag nanoparticles have been studied. The following main parts are included in this paper:1. The spinning properties of PVA aqueous solution by adjusting the solution concentration, spinning voltage and the tip-to-collector distance are studied. The results show that: a suitable concentration of PVA is 7wt%. Diameter of nanofibers decreases with increasing spinning voltage. There is almost no change of nanofibers with increasing tip-to-collector distance.2. PVA/AgNO3 nanofibers are prepared by electrospinning technology. The spinning properties of nanofibers and size distribution of Ag nanoparticles are studied. The results show that: after adding silver nitrate, the diameter of nanofibers decreases and a lot of beaded structures appear in fibers. Well-dispersed Ag nanoparticles are generated in nanofibers and the size distribution is narrow. There is no change of FT-IR with and without adding silver nitrate. Mechanical properties of PVA films are improved with increasing silver content.3. SF and PVA solutions were prepared respectively by formic acid and deionized water as solvent, the solutions were then blended, and after that AgNO3 was added. The PVA/SF/AgNO3 blend solution was electrospun to prepare nanofibers. The properties of nanofibers and size distribution of Ag nanoparticles are studied. The results show that: diameter distribution of nanofibers is narrow when the blend ratio of PVA/SF is 80/20. Well-dispersed Ag nanoparticles are generated in situ in composite nanofibers without post treatment. The size distribution is narrow and the size increases with increasing silver content and decreasing ratio of SF in nanofibers. There is enhanced interaction between PVA and SF after blend. Mechanical properties of PVA/SF blend films are impoved with increasing silver content and increasing PVA ratio.4. PVA/SF composite nanofibers containing Ag nanoparticles are treated with heat-treating at 155℃for 5min and subsequent UV irradiating at 365nm for 3h. Effect of post treatment on composite nanofibers and Ag nanoparticles is discussed. The results show that: PVA nanofibers could preserve the web structure in water after the heat treatment. Color of nanofiber webs is changed from white to light yellow after the heat treatment, and changed into tawny after subsequent UV irradiation. Diameter of nanofibers decreases and size of Ag nanoparticles increases after post treatment. A new X-ray diffraction peak appears after UV irradiation. The size of Ag nanoparticles increased by prolonging the time of heat-treated. These are effective measures to control the size of Ag nanoparticles by adjusting the ratio of SF, silver content and time of the heat treatment.