Preparation of photoresponsive lanthanide aluminate-immobilized nanofibers from recycled bioplastic via solution blowing spinning for optical authentication labeling

Abstract

Photochromism is an intriguing technology to enhance the authentication of various commercial materials. In order to produce a transparent authentication film, it is also significant to improve the engineering process of anti-counterfeiting materials. In contrast to electrospinning, the solution blowing spinning (SBS) technique has been recently developed to produce nanofibers at low-cost and high yield with no need to apply high voltage. It has been essential to reduce the toxic pollution caused by plastic waste. Herein, we develop a photoluminescent nanofibrous membrane from recycled polylactic acid (PLA) waste and nanoparticles of strontium aluminate (NSA) by using the simple SBS technique. We investigated the potential use of the NSA@PLA composite nanofibers for photochromic anti-counterfeiting driven by ultraviolet light. Encapsulating the nanoparticle form of the strontium aluminate phosphor into polylactic acid nanofibers is necessary to ensure the transparent characteristic of the nanofibrous film. The film transparency can be further improved by the efficient dispersion of NSA without aggregation in the polylactic acid solution. Nanofibrous membranes with varying emission characteristics were produced by varying the NSA ratio. Both of X-ray diffraction (XRD) and Transmission electron microscopy (TEM) demonstrated the morphology of NSA to show diameters of 5–12 nm. The morphologies of the nanofibrous membranes were examined using various analytical methods, including energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence spectroscopy (XRF) and scanning electron microscopy (SEM). The mechanical characteristics and optical luminescence were also examined. SEM analysis of the NSA@PLA nanofibers showed diameters of 100–220 nm. The NSA@PLA nanofibrous membranes exhibited an emission peak at 518 nm upon excitation at 365 nm. The contact angles of the NSA@PLA nanofibrous membranes increased from 138.2° to 144.5° as the NSA concentration was increased, indicating an improved superhydrophobicity. Exposure to ultraviolet light caused the transparent nanofibers to undergo a rapid and strongly reversible photochromism to greenish emission. The present study can be reported as an easy and efficient approach to create anti-counterfeiting materials that offer a perfect market with social and financial profits.