Multi‐Responsive Polymer Nanoparticles: A Versatile Platform for Double‐Security Anticounterfeiting and Smart Food Packaging

Potential applications of colloidal polymer nanoparticles in the preparation of smart inks are investigated by physical incorporation of the oxazolidine molecules. Precise adjusting the polymer chain flexibility and polarity is achieved by controlling the ratio of methyl methacrylate and butyl acrylate monomers in the polymerization reaction. In addition, nanofibrous indicators of acid-base vapors are prepared from the latex nanoparticles. This can be beneficial for creating materials that sense and respond to environmental changes, such as humidity or moisture and acidity. Thermochromic inks are prepared by microencapsulating crystal violet lactone dye (CVL) in polymer matrices to prevent their release into the aqueous media. Combining two distinct systems with varying triggers, such as light and temperature, provides an effective strategy for double-encryption anticounterfeiting and crack and scratch detection and indication applications. Preparing labels impregnated with double-responsive inks, a novel approach is developed for food spoilage detection and preservation indication. Labels are manufactured using polymer nanoparticles, which contain photoluminescent oxazolidine molecules, as well as a trinary mixture of CVL within core-shell latex particles as the thermochromic dye. The combination of these two responsive elements transforms traditional packaging into a dynamic and interactive sentinel for the food it holds.