Orthogonal Photo‐ and Thermo‐Responsive Fluorescent Polymeric Hydrogels for Multi‐Level Information Encryption and Anti‐Counterfeiting

Abstract Stimulus‐responsive fluorescent polymeric materials (FPMs) that can change their fluorescent states via external stimuli have been widely applied in multi‐level information encryption and anti‐counterfeiting. While many efforts have mainly focused on the design of dual‐stimuli responsive FPMs, the construction of orthogonal photo‐ and thermo‐regulation of fluorescent polymeric systems remains a challenge. Here, the orthogonal photo‐ and thermo‐responsive fluorescent polymeric hydrogels (PTFPHs) containing capsules with the phase change materials (PCMs), photoresponsive molecules (DTE), and thermally responsive molecules (TPA‐DCPP) are reported. They are capable of reconfiguring fluorescence (none, green, yellow, red) via photo‐ and thermo‐induced fluorescence resonance energy transfer (FRET) process. Additionally, not only can the thermochromic property of PTFPHs be regulated by modulating the composition of PCMs, but the thermochromic and photochromic properties of PTFPHs can also be tuned by using SDS to control the size of capsules. The developed hydrogels exhibited high fluorescence contrast, fast response, and excellent reversibility. The PTFPHs are successfully applied in multi‐level information encryption and integrated application between temperature monitoring and anti‐counterfeiting. The works represented a strategy for developing multi‐stimuli responsive PTFPHs in multi‐level information encryption and advanced anti‐counterfeiting.