Moisture-resistant nitroaromatic explosive gas sensor based on hydrophilic pentiptycene polymer

The detection of explosive materials, particularly nitroaromatic compounds such as 2,4,6-trinitrotoluene (TNT), is critical for public safety and national security. Existing detection methods often require complex instrumentation, limiting their applicability for real-time or in-field use. Fluorescent sensors, which offer rapid and sensitive detection through fluorescence quenching, present a promising alternative. This study evaluates the performance of two pentiptycene-based polymers, P-1 and P-2, in detecting explosive vapors, with a specific focus on their behavior under high-humidity conditions. P-2, modified with triethylene glycol groups, demonstrated significantly increased hydrophilicity compared to the commonly studied P-1, as confirmed by contact angle measurements. Spectroscopic analysis revealed a blue shift in P-2's UV–Vis absorption and photoluminescence spectra, indicating electronic property changes due to structural modifications. The enhanced hydrophilicity of P-2 enabled it to maintain stable sensing performance under moist conditions, showing less than a 10% reduction in sensitivity, compared to the 20% decrease observed in P-1. This superior moisture resistance suggests that P-2 is a more robust and practical sensor for explosive detection in environments with variable humidity levels.