Preparation and properties of zeolitic imidazolate framework ZIF-L/PVA composite films

Because of the unique structure and function of zeolitic imidazolate frameworks (ZIFs), the utilization of ZIFs to enhance the properties of polymer and prepare new functional composites have attracted growing attention. To clarify the reinforcing effects of ZIFs on poly(vinyl alcohol) (PVA), zeolitic imidazolate framework ZIF-L was used as reinforcer and series of PVA composite films with different concentrations of ZIF-L were prepared by solution casting process. The structure, optical properties, mechanical properties, color, barrier performance and thermostability of the composite films were analyzed. The results indicate that the composite films show an enhanced anti-ultraviolet property with the addition of ZIF-L. The tensile strength initially increases and then decreases with increasing content of ZIF-L while the water vapor permeability and thermal degradation temperature show an opposite tendency. In addition, the incorporation of ZIF-L increases the oxygen permeability of the films gradually. When the ZIF-L content is 1wt%, the tensile strength of the composite film is increased by about 15%, while the water vapor permeability is reduced by 1.8%, ZIF-L significantly enhances the properties of PVA and the composite film show good comprehensive performance. When the ZIF-L content is larger than 5wt%, the maximum decomposition temperature begins to increase and reaches up to 297.84℃. The ZIF-L reinforced PVA composites in the present work will advance the development of new functional packaging composite films.