The Polymer Society of Korea

Abstract

Ammonia (NH₃) is widely used in industrial and agricultural fields, but it is considered a hazardous substance due to its toxicity. According to the Occupational Safety and Health Administration (OSHA), exposure exceeding 25 ppm over 8 hours or 35 ppm over 15 minutes is unsafe. NH₃, a major contributor to environmental pollution, is also generated during food spoilage and can serve as a useful indicator for monitoring meat freshness. In this study, a cytosine-functionalized diacetylene monomer (CyDA) was synthesized, which formed a self-assembled structure through hemi-protonation and was polymerized into blue-phase polydiacetylene (CyPDA-H) upon UV irradiation. Using this material, a 3D nanofiber structure was fabricated via electrospinning. The resulting structure exhibited high sensitivity to ammonia gas with a detection limit of 17 ppm, showing a distinct blue-to-red color change. When tested with fresh chicken at 25 °C, a clear color shift was observed over time, demonstrating its potential as a food freshness indicator for smart packaging applications.