PHOTOLUMINESCENCE OF PYRENEBUTYRIC ACID INCORPORATED INTO SILICONE FILM AS A TECHNIQUE IN LUMINESCENT OXYGEN SENSING

The photoluminescence of pyrenebutyric acid (PEA) incorporated into a cast silicone film has been studied, and the structural features around the luminescent molecule are discussed. The III/I peak intensity ratio of the emission spectrum was higher for the film than for PEA solution, indicating that the PEA in the silicone film existed in a nonpolar micro-environment. The III/I ratio was dependent on both the evaporation of the cast solvent and the drying conditions of the film, which was ascribed to the remaining trace cast solvent in contact with PEA. The long emission lifetime of PEA in the slow-evaporation film showed that its local molecular mobility is suppressed by tight molecular packing, The amount of PEA extracted from the film using water increased with increase in the polarity of the cast solvent, suggesting that different cluster and channel structures are formed depending upon the cast solvent used, The efficiencies of the emission quenching by oxygen were similar for the films prepared by different cast solvent, The linear Stern-Volmer plots for the quenching by oxygen showed that a luminescent oxygen sensor can be fabricated by a simple mixture-casting method, Other characteristics of using PEA films as oxygen sensors, such as, sensitivity, detection limit and response time etc., are also discussed.