Eco-friendly fabrication and luminescent properties of flexible Ag–In–Zn–S/ZnS QD-WPU composite film

With the advancement of economic development and the increasing complexity of commodity distribution, efficient and precise anti-counterfeiting measures have garnered significant attention in recent decades. This challenge necessitates the development of flexible films exhibiting both superior mechanical and optical properties to accommodate various anti-counterfeiting applications. This study introduces a composite film comprised of waterborne polyurethane (WPU), gelatin quantum dots (QDs), and glycerol. Glycerol, employed as a plasticizer, enhances the film's plasticity by disrupting hydrogen bonds within the matrix. The tensile strength decreased from 7.7 MPa to 1.73 MPa, while the elongation at break increased from 410 % to 656 %, compared to the samples without glycerol. The resulting films exhibit advantageous properties, including facile preparation, high transmittance, excellent optical properties, and excellent mechanical performance. Additionally, the photoluminescence intensity decreased by only 15 % after being placed in air for 30 days. They demonstrate commendable stability under ambient temperature and environmental conditions, making them suitable for diverse and intricate anti-counterfeiting applications. The emission wavelength of the composite films was tuned by adjusting the cation ratio of the QDs, and the mechanical properties can be adjusted by varying the QD and glycerol contents. This work offers valuable insights for the development of advanced flexible materials for anti-counterfeiting purposes.