Aggregation-induced emission-active hyperbranched polymers conjugated with tetraphenylethylene for nitroaromatic explosive detection

This work develops a facile synthesis for aggregation-induced emission (AIE)-active hyperbranched polyglycidols (HPGs) to design a solid-state sensor for detecting nitroaromatic explosives. The tetraphenylethylene moieties were conjugated onto the periphery of the HPGs in a single step using dynamic boronate ester cross-linkers. The resulting AIE-active HPGs exhibited excellent AIE characteristics in tetrahydrofuran (THF)/H2O mixtures, emitting a strong blue fluorescence under UV irradiation. Dynamic light scattering and transmission electron microscopic analyses demonstrated that the self-assembled nanosized aggregates were stable in the THF/H2O mixture. The fluorescence of the aggregates was dramatically quenched by various nitro compounds, including 2,4,6-trinitrophenol (or picric acid; PA), 2,6-dinitrophenol, 4-nitrophenol, 4-nitrotoluene, and nitromethane. The nano-aggregates exhibited extraordinary sensitivity towards PA, with a Stern-Volmer constant (Ksv) of 2.27 x 104 M-1 and a limit of detection of 40 ppb. Paper strips encapsulating the aggregates exhibited a vivid visual quenching, promising the practical applicability of these polymers as solid-state sensors for the detection of nitroaromatic explosives.