Study Of Preparation And Properties Of Poly（Vinyl Alcohol）/Silk Fibroin/Nano-SiO₂Hybrid Films

In recent years, with the development of nanoscience and technology,nanomaterials and nanotechnology were applied in polymer modified owing to thestrong interfacial interactions between inorganic nanoparticles and polymer arising fromthe nature of sound, light, electricity, magnetism. In this paper, effect of nano-silica（nano-SiO₂） on the morphology and properties of polyvinyl alcohol （PVA）/silk fibroin（SF） blend were studied as follows:（1） The preparation of nano-SiO₂. Different catalytic media on the morphology andstructure of nano-SiO₂were studied. The results showed that irregular silica particleswith wide size distribution were obtained in the acidic catalytic media, while, sphericalsilica particles were obtained with a narrow diameter distribution in alkaline medium.（2） The effect of nano-SiO₂on Poly （vinyl alcohol）/silk fibroin blend membranes.The morphology, structure and properties of the blend were analyzed by scanningelectron microscopy （SEM）, transmission electron microscopy （TEM）, fouriertransform infrared spectroscopy （FTIR）, X-ray diffraction （XRD）, differential scanningcalorimetry analysis （DSC）, thermogravimetric analysis （TGA）, and test of mechanicalproperties. The results show that the effect of nano-SiO₂obtained by acidic catalyticmedia on the compatibility of PVA/SF blend was better, and the nano-particles werewell distributed in PVA/SF plomyer matrix. The thermal and mechanical properties ofPVA/SF blend were also improved.（3） The morphology and properties of electrospun PVA/SF/SiO₂fiber mats. SiO₂was added in PVA/H2O and SF/HCOOH blend solution, then, PVA/SF/SiO₂fiber matswas prepared by electrospinning. The morphology, structure, and properties of fibermats were analyzed. We found the spinnability, thermal properties of PVA/SF blendwere improved and the crystallinity was decreased due to the formation of interactionsbetween PVA and SF by adding SiO₂. When the ratio of PVA and SF is50/50, the fibersshowed straight and smooth surface, and the diameter distribution was also narrow. Asthe content of SiO₂increased, the diameter of electrospun fibers was first bigger, andthen the spinnability became bad when the content of SiO₂was5wt.%. （4） Effect of post-processing on the structure and properties of PVA/SF/SiO₂fibermats. Fiber mats were heat treated in155oC for30min and immersed in methanolsolution for10min. The two-step post-processing of the fiber mats was discussed. Theresults indicated that the fibers can maintain fiber network structure in water after heattreatment, and melting loss was significantly reduced. FTIR illustrated thecomformation of SF was transformed from silk I to silk II after immersed in methanol.