Polypeptide Interlocking Organic Phosphorescent Materials with Superior Moisture and High Temperature Resistance

Biobased polymers with abundant hydrogen bond sites, excellent biocompatibility, and degradability are expected to serve as promising matrices for organic phosphorescent materials, thereby overcoming the hard degradation of petrochemical-based matrices. However, biobased polymer phosphorescent materials suffer from inadequate moisture and high temperature resistance, substantially limiting their application scenarios. Herein, a series of polypeptide-based phosphorescent films were successfully constructed by self-assembly of carboxyl-rich γ-polyglutamic acid, amino-rich ε-polylysine, and amphoteric guest molecules. These films exhibited multicolor phosphorescence emission with ultralong lifetime of up to 1139 ms. Notably, the optimal material demonstrated superior moisture resistance by retaining 94% phosphorescence intensity and 98% lifetime after steam fumigation, while exhibiting remarkable high temperature resistance by maintaining a 4 s afterglow at 393 K. Further experiments revealed that the carboxyl-amino pair formed a stable interlocking hydrogen bond structure, thereby enhancing the hydrophobicity of the materials. Additionally, the guest molecules were synergistically anchored through hydrogen bonds and electrostatic interactions with the matrix, effectively retaining phosphorescence emission of the composite material at a high temperature. Moreover, based on their pH response and dynamic phosphorescence performance, an attempt was made to use these materials for pattern anticounterfeiting and rapid quantitative detection of acidic/basic gases.