An essential factor for the creation of oxygen sensors based on luminescence quenching is the long-term stability of the
parameters determining the luminescence decay. In the present work, the effects of material aging and photobleaching on
decay parameters are studied for Pd-tetraphenylporphyrin and Pd-pentafluoro-tetraphenylporphyrin molecules embedded
into different polymer films. In polymethylmethacrylate host the decay was well described by stretched exponent
function. During annealing of PMMA films at different temperatures between 20 and 70 °C during 9 months a
logarithmic decrease of the material sensitivity occurred due to the physical aging of the polymer. The photostability
studies of PMMA films showed an opposite effect: the photobleaching was accompanied by a decrease in natural decay
time, whereas the oxygen sensitivity remained practically constant. Luminescence quenching in polystyrene and
polycarbonate films had different character as compared to PMMA, and was interpreted with a two-site model, combined
with a nonlinear gas transport model. In these polymer hosts the oxygen sensitivity increased during the first stage of
aging, which was ascribed to the changes in the Langmuir component of gas transport, i.e., to the evaluation of
microvoids in these glassy polymers.
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