Preparation of color-tunable electrospun cellulose acetate-polycaprolactone nanofibrous film for information encryption

Novel photochromic and long-persistent photoluminescent electrospun nanofibrous films were developed for anticounterfeiting applications. The inclusion of rare-earth activated strontium aluminum oxide (RSAO) nano-scaled particles into nanofibers of cellulose acetate-polycaprolactone (CA-PCL) composite facilitated the development of a simple method for creating an organic-inorganic photoluminescent nanocomposite. Upon excitation at 365nm, the luminescent nanofibrous films showed an emission band of 516nm. The current from photochromic films change color to green when illuminated with ultraviolet light as proved by absorption and fluorescence analyses, and CIE Lab parameters. Both mechanical and hydrophobic properties of the electrospun films were found to improve with raising RSAO content in CA-PCL. Improved hydrophobic performance was monitored without any compromise to their other desirable properties. The morphology of the synthesized phosphor nanoparticles was investigated to indicate particle diameter of 2-12nm, whereas the morphology of the electrospun nanofibers displayed diameters of 200-300nm. The cytotoxicity of RSAO was also explored using the MTT proliferation assay. When exposed to UV, the nanofibrous films showed reversible photochromism without fatigue