Microwave absorbing fluorescent copolymer with enhanced anti‐counterfeiting security features.

Abstract

Counterfeiting is a significant issue affecting various sectors, including banking, insurance, pharmaceuticals, and commercial goods. A combination of security elements creates a multilayered protection for counterfeiting prevention, ensuring diverse authentication against fraud and unauthorized duplication. To design microwave-absorbing polymers with optical transparency and fluorescence, methyl methacrylate (MMA) was copolymerized using reversible addition-fragmentation chain transfer (RAFT) polymerization with 2-(dimethylamino)ethyl methacrylate (DMAEMA) and pyrene methacrylate (PyMA). The amine moieties from the DMAEMA repeating units in the copolymer were ionized at room temperature by treating with hydrochloric acid (HCl) or trifluoroacetic acid (TFA), resulting in copolymer salts with an ion-pair complex. Optical transparency, fluorescent properties, and ionic conductivity of the copolymer salts with chloride (Cl⁻)/trifluoroacetate (TFA−) counter anions and pyrene moieties were studied in detail. Optically transparent fluorescent copolymers with partially mobile Cl⁻ counter anions witnessed strong microwave absorption due to multiple reflections from structural and physical anisotropies. This study highlights a strategy for designing a material that combines multiple features like microwave absorption, optical transparency, and characteristic fluorescence emission, within a single material system, a key area of research in the security and communication industries.